How big of a deal is it if I abbreviate a school name? I am writing some thank you's for interviews I had recently. How big of a deal is it if I write UCLA instead of University of California at Los Angeles, for example? I have always spelled things out in cover letters and CVs and stuff, but especially at this point, it just seems like I should just be able to write UCLA. Would anyone not think kindly of this?

Some school names are short/you should always write out like University of Michigan instead of Michigan, or University of South Carolina instead of USC, but when there's no ambiguity like UCLA, it seems silly to write that out every time.

Thanks for the help!

P.s. these are for math positions if that matters.
I can't imagine that anyone would object, as long as the abbreviation is widely used by people who work at the university.  (UCLA is fine, but I wouldn't call it UC Los Angeles, since I believe that's a much less common abbreviation.)

In fact, repeatedly writing out "University of California, Los Angeles" is more likely to stand out as strange than using the abbreviation UCLA is.