Fortunately, there was a LaTeX style file that had been handed around the physics department for years that generations of grad students had tuned to meet the requirements. Doing my part, I tweaked it a bit to handle some special cases that came up in my thesis (and, I think, to clean up the code in one or two places) and passed it on to the next generation. (I shudder to think of how many forks there must have been; I saw at least two or three while I was preparing my version. Maybe someone has put a canonical version on GitHub by now: nothing of the sort was really on our radar back then.)

I've heard of one university (there must be others) where there's a thick compendium that specifies exactly which font to use where on each page, what spacings and margins to use, how to format the table of contents, etc. Not actually a LaTeX stylesheet you can use, but a list of rules that you manually have to make sure your thesis conforms with. Of course, the rules were written with MS Word in mind, but math/CS/science people who need to use LaTeX have to replicate the rules in detail. Of course, there's a person employed by the university to check that your submitted thesis exactly conforms with the rules, or else it will be rejected.

The person who told me this might have embellished the story, but sadly it sounds all too plausible to me.

My university doesn't even provide this front page in LaTex ...