Fun story: when I was applying for game jobs in 1994 I sent a 3.5” demo disk with my CV. It had a few little ModeX asm demos, but the piece de resistance was a sort of in-between-Wolfenstein-and-Doom engine. I was quite pleased with it even though it wasn’t half as good as iD’s stuff (who was, except Ken Silverman?)
Anyway I’d made a bunch of disks and sent them off with my CV. A week or so after lots of rejections I discovered a mistake which, when fixed, roughly doubled the frame rate. 😩