In Shemos 18:21 Yisro tells Moshe that he shouldn't judge Bnei Yisrael himself, instead he should appoint:
וְאַתָּ֣ה תֶחֱזֶ֣ה מִכָּל־הָ֠עָם אַנְשֵׁי־חַ֜יִל יִרְאֵ֧י אֱלֹהִ֛ים אַנְשֵׁ֥י אֱמֶ֖ת שֹׂ֣נְאֵי בָ֑צַע וְשַׂמְתָּ֣ עֲלֵהֶ֗ם שָׂרֵ֤י אֲלָפִים֙ שָׂרֵ֣י מֵא֔וֹת שָׂרֵ֥י חֲמִשִּׁ֖ים וְשָׂרֵ֥י עֲשָׂרֹֽת׃ You shall also seek out from among all the people capable men who fear God, trustworthy men who spurn ill-gotten gain. Set these over them as chiefs of thousands, hundreds, fifties, and tens,
Rashi gives us the math:
שרי אלפים. הֵם הָיוּ שֵׁשׁ מֵאוֹת שָׂרִים לְשֵׁשׁ מֵאוֹת אֶלֶף:
שרי מאות. שֵׁשׁ אֲלָפִים הָיוּ:
שרי חמשים. י"ב אֶלֶף:
שרי עשרת. שִׁשִּׁים אֶלֶף:
שרי אלפים OFFICERS OF THOUSANDS — there were six hundred such officers for the six hundred thousand men of Israel. שרי מאות OFFICERS OF HUNDREDS — there were six thousand of them. שרי חמשים OFFICERS OF FIFTIES — twelve thousand. שרי עשרת OFFICERS OF TENS — sixty thousand (Mekhilta d'Rabbi Yishmael 18:21:2, Sanhedrin 18a).
The total amount of judges Yisro recommends to replace Moshe is 78,600 (60,000+12,000+6,000+600). Why on Earth would 600,000 people need 78,600 judges?
Keep in mind that until now Moshe was doing it all himself and he was perfectly fine with it and expected Klal Yisrael to also be perfectly fine with it. I understand that it's much too much for one person, but several hundred judges or even several thousand judges should have been more than adequate.