I've never seen the Crash source code, so was making my statements based on second hand knowledge. So thanks for that clarification. I do think it's worth pointing out that Naughty Dog and Insomnia were two companies well known for making highly optimized software for the PSX; so probably not a standard most other companies matched.

Additionally, I have written my own PSX software as well as reviewed plenty of contemporaneous PSX software. While many have some bit of assembler, it's usually specifically around the graphics pipeline. About 90+% of all code is C. This is in line with interviews from developers at the time, as well.

The point wasn't that ASM wasn't used at all (in fact, I specifically acknowledged it in my original post), it was that the PSX was in an era passed the time when entire codebases were hand massaged/tuned assembler (e.g. "the 16-bit era" and before).

Insomniac was down the hall from us when we wrote Crash 1 and yes, the Hastings brothers definitely wrote some very tight assembly code!