Generally speaking, how should one interpret Mishnayos that go off-tangent?

Question

To pose a few examples of the types of Mishnayos I'm speaking about:

• Pesachim 4:1-5 discusses various activities which depend on the local custom, most of which have nothing to do with Pesach
• Gittin 4:2-5:9 discusses various activities done for improving public welfare and peace (and some of these Mishnayos are tangents off of tangents!), most of which have nothing to do with divorce
• Megillah 1:4-11 discusses various pairs of items which are generally similar, except for a couple of differences, most of which have nothing to do with Purim
• Erchin 2:1-6 lists various things which can be no less than some amount but no more than some other amount, most of which have nothing to do with donations to the Beis HaMikdash
• Erchin 3:1-5 lists various things which have leniencies and stringencies over other things, most of which still have nothing to do with donations to the Beis HaMikdash

etc. etc.

I see two ways to interpret these kinds of tangents on a general basis, each of which poses questions to be answered on a case-by-case basis.

1. Mishnayos are ordered to make it easier to memorize, and often similar-ish topics are put together just so that it's easy to remember. So, once we bring up the topic, we discuss all similarly-posed discussions. The follow-up question is why we often don't exhaust the list.
2. Really, there is an inherent connection between all of the items on the list beyond that they can be phrased similarly. The follow-up question is often what that connection is.

Do any Mefarshim comment on this pattern and give either of the above interpretations (or another one)?

Answer 1

It's because the Mishna is Oral Torah, not written Torah. The Mishna preserves the way the Oral Law was learned before it was written down.

For instance, in Shevuot it starts by talking about two oaths that are four and continues with many other things that are two () that are four. You wouldn't write a book this way, but a conversation could easily proceed in such a manner.

Answer 2

The Tosfos Yom Tov (Shekalim 1:3) seems to hold like my first approach, by addressing why that Mishnah doesn’t appear in Gittin.

מפני דרכי שלום. ... ונראה לי דהיינו דרכי שלום שאם לא נחלוק להם כבוד אתו לאנצויי ולפי שאין כאן דרכי שלום אלא א"כ שנקדים מסברא שראוי לחלוק להם כבוד הלכך לא נשנה בפרק ה' דגיטין גבי הנהו דקתני התם דמפני דרכי שלום

And it appears to me that that is “ways of peace,” for if we don’t give them honor, they will come to make arguments. Since there is no “ways of peace” unless we first pose the logic that it’s fitting to accord them honor, therefore it’s not taught in Chapter 5 of Gittin regarding all cases where it’s taught by them that they are because of “ways of peace.”