We accidentally discovered the max number of assets circa 2011 in a very large Rails app in development mode (which loaded CSS/JS files individually without concatenation). I forgot what it was but it was much lower than you'd anticipate.
4,096 iirc, and i also was one to arbitrarily split files lol
I think I got hit by that being not exactly 4096. Some elements would grab a selector handle, then disappear, but take the handle with them. It's been too long, and my memory is too crap, to be sure. But I think I sat there growling cursewords for a few days until I worked that one out.