There is a definite Talmudic belief that there are no unnecessary statements in the Torah. See Sanhedrin 99b
Our Rabbis taught: But the soul that doeth aught presumptuously: this refers to Manasseh the Son of Hezekiah, who examined [Biblical] narratives to prove them worthless. Thus, he jeered, had Moses nothing to write but, And Lotan's sister was Timna, And Timna was concubine to Eliphaz, And Reuben went in the days of the wheat harvest, and found mandrakes in the field. Thereupon a Heavenly Voice cried out: Thou sittest and speakest against thy brother; thou slanderest thine own mother's son. These things hast thou done, and I kept silence, thou thoughtest that I was altogether such an one as thyself' but I will reprove thee, and set them in order before thine eyes. And of him it is explicitly stated in the post-Mosaic Scriptures, Woe unto them that draw iniquity with cords of vanity, and sin as it were with a cart rope. What is meant by 'and sin as it were with a cart rope'? — R. Assi said: Temptation at first is like a spider's thread, but eventually like a cart rope.
À propos, what is the purpose of [writing], And Lotan's sister was Timna? — Timna was a royal princess, as it is written, alluf [duke] Lotan, alluf [duke] Timna; and by 'alluf' an uncrowned ruler is meant. Desiring to become a proselyte, she went to Abraham, Isaac and Jacob, but they did not accept her. So she went and became a concubine to Eliphaz the son of Esau, saying, 'I had rather be a servant to this people than a mistress of another nation.' From her Amalek was descended who afflicted Israel. Why so? — Because they should not have repulsed her.
And Reuben went in the days of the wheat harvest [and found mandrakes in the field]. Raba b. Isaac said in Rab's name: This shews that righteous men do not take what is not theirs.
This idea is elaborated upon in Rambam's Guide To The Perplexed part 3 chapter 50
THERE are in the Law portions which include deep wisdom, but have been misunderstood by many persons.; they require, therefore, an explanation. I mean the narratives contained in the Law which many consider as being of no use whatever; e.g., the list of the various families descended from Noah, with their names and their territories (Gen. x.); the sons of Seir the Horite (ibid. xxxvi. 20-30); the kings that reigned in Edom (ibid. 31, seq.); and the like. There is a saying of our Sages (B Ṭ. Sanh. 99b) that the wicked king Manasse frequently held disgraceful meetings for the sole purpose of criticising such passages of the Law. "He held meetings and made blasphemous observations on Scripture, saying, Had Moses nothing else to write than, And the sister of Lotan was Timna" (Gen. xxxvi. 22)? With reference to such passages, I will first give a general principle, and then discuss them seriatim, as I have done in the exposition of the reasons of the precepts. Every narrative in the Law serves a certain purpose in connexion with religious teaching. It either helps to establish a principle of faith, or to regulate our actions, and to prevent wrong and injustice among men; and I will show this in each case. It is one of the fundamental principles of the Law that the Universe has been created ex nihilo, and that of the human race, one individual being, Adam, was created. As the time which elapsed from Adam to Moses was not more than about two thousand five hundred years, people would have doubted the truth of that statement if no other information had been added, seeing that the human race was spread over all parts of the earth in different families and with different languages, very unlike the one to the other. In order to remove this doubt the Law gives the genealogy of the nations (Gen. v. and x.), and the manner how they branched off from a common root. It names those of them who were well known, and tells who their fathers were, how long and where they lived. It describes also the cause that led to the dispersion of men over all parts of the earth, and to the formation of their different languages, after they had lived for a long time in one place, and spoken one language (ibid. xi.), as would be natural for descendants of one person. The accounts of the flood (ibid. vi.-viii.) and of the destruction of Sodom and Gomorrah (ibid. xix.), serve as an illustration of the doctrine that "Verily there is a reward for the righteous; verily He is a God that judgeth in the earth" (Ps. lviii. 12).
The narration of the war among the nine kings (ibid. xiv.) shows how, by means of a miracle, Abraham, with a few undisciplined men, defeated four mighty kings. It illustrates at the same time how Abraham sympathized with his relative, who had been brought up in the same faith, and how he exposed himself to the dangers of warfare in order to save him. We further learn from this narrative how contented and satisfied Abraham was, thinking little of property, and very much of good deeds; he said, "I will not take from a thread even to a shoe-latchet" (Gen. xiv. 23).
The list of the families of Seir and their genealogy is given it the Law (ibid. xxxvi. 20-36), because of one particular commandment. For God distinctly commanded the Israelites concerning Amalek to blot out his name (Deut. xxv. 17-19). Amalek was the son of Eliphas and Timna, the sister of Lotan (ibid. xxxvi. 12). The other sons of Esau were not included in this commandment. But Esau was by marriage connected with the Seïrites, as is distinctly stated in Scripture: and Seïrites were therefore his children: he reigned over them; his seed was mixed with the seed of Seir, and ultimately all the countries and families of Seir were called after the sons of Esau who were the predominant family, and they assumed more particularly the name Amalekites, because these were the strongest in that family. If the genealogy of these families of Seir had not been described in full they would all have been killed, contrary to the plain words of the commandment. For this reason the Seirite families are fully described, as if to say, the people that live in Seir and in the kingdom of Amalek are not all Amalekites: they are the descendants of some other man, and are called Amalekites because the mother of Amalek was of their tribe. The justice of God thus prevented the destruction of an [innocent] people that lived in the midst of another people [doomed to extirpation]; for the decree was only pronounced against the seed of Amalek. The reason of this decree has already been stated by us The kings that have reigned in the land of Edom are enumerated (Gen xxxvi. 51, seq.) on account of the law, "Thou mayst not set a stranger over thee, which is not thy brother" (Deut. xvii. 15). For of these kings none was an Edomite; wherefore each king is described by his native land; one king from this place, another king from that place. Now I think that it was then well known how these kings that reigned in Edom conducted themselves, what they did, and how they humiliated and oppressed the sons of Esau. Thus God reminded the Israelites of the fate of the Edomites, as if saying unto them, Look unto your brothers, the sons of Esau, whose kings were so and so, and whose deeds are well known. [Learn therefrom] that no nation ever chose a foreigner as king without inflicting thereby some great or small injury upon the country. In short, what I remarked in reference to our ignorance of the Sabean worship, applies also to the history of those days. If the religious rules of the Sabeans and the events of those days were known to us, we should be able to see plainly the reason for most of the things mentioned in the Pentateuch.
Rambam there goes on to say
It is also necessary to note the following observations. The view we take of things described by others is different from the view we take of things seen by us as eye-witnesses. For that which we see contains many details which are essential, and must be fully described. The reader of the description believes that it contains superfluous matter, or useless repetition, but if he had witnessed the event of which he reads, he would see the necessity of every part of the description. When we therefore notice narratives in the Torah, which are in no connexion with any of the commandments, we are inclined to think that they are entirely superfluous, or too lengthy, or contain repetitions; but this is only because we do not see the particular incidents which make those narratives noteworthy. Of this kind is the enumeration of the stations [of the Israelites in the wilderness] (Num. xxxiii.). At first sight it appears to be entirely useless; but in order to obviate such a notion Scripture says, "And Moses wrote their goings out according to their journeys by the commandment of the Lord" (ibid. ver. 2). It was indeed most necessary that these should be written. For miracles are only convincing to those who witnessed them; whilst coming generations, who know them only from the account given by others, may consider them as untrue. But miracles cannot continue and last for all generations; it is even inconceivable [that they should be permanent]. Now the greatest of the miracles described in the Law is the stay of the Israelites in the wilderness for forty years, with a daily supply of manna. This wilderness, as described in Scripture, consisted of places "wherein were fiery serpents and scorpions, and drought, where there was no water" (Deut. viii. 115); places very remote from cultivated land, and naturally not adapted for the habitation of man, "It is no place of seed, or of figs, or of vines, or of pomegranates, neither is there any water to drink" (Num. xx. 5); "A land that no man passed through, and where no man dwelt" (Jer. ii. 6). [In reference to the stay of the Israelites in the wilderness], Scripture relates, "Ye have not eaten bread, neither have ye drunk wine or strong drink" (Deut. xix. 5). All these miracles were wonderful, public, and witnessed by the people. But God knew that in future people might doubt the correctness of the account of these miracles. in the same manner as they doubt the accuracy of other narratives; they might think that the Israelites stayed in the wilderness in a place not far from inhabited land, where it was possible for man to live [in the ordinary way]; that it was like those deserts in which Arabs live at present; or that they dwelt in such places in which they could plow, sow, and reap, or live on some vegetable that was growing there; or that manna came always down in those places as an ordinary natural product; or that there were wells of water in those places. In order to remove all these doubts and to firmly establish the accuracy of the account of these miracles, Scripture enumerates all the stations, so that coming generations may see them, and learn the greatness of the miracle which enabled human beings to live in those places forty years.
Concerning the doubled words in the Torah, although it is true we find the phrase in the Talmud 'Dibra Torah Kilashon Benei Adam' used as a way of explaining why we do not expound the doubled expression under scrutiny, we find many times that the Talmud does expound upon doubled expressions. And in fact the same person, Rabi Shimon, is found both stating that we can expound doubled words and stating not to expound doubled words because of Dibra Torah etc.
Tosafos in Bava Metzia 31b s.v. Dibra Torah therefore explain that we only say Dibra Torah etc. when there is evidence in the passuk to say so. But otherwise any doubling is considered open for expounding, and not simply extra.