If you're an engineer it can be quite shocking to see how people like the author work. It's much more like science than engineering. A lot of trial and error and swapping things around without fully understanding the implications etc. It doesn't interest me, but it's how all the best results are obtained in ML as far as I can tell.
I'm a scientist and I'd never work that way. I'm methodical, because I've learned it's the fastest and highest-ROI approach.
Guessing without understanding is extremely unlikely to produce the best results in a repeatable manner. It's surprising to me when companies don't know that. For that reason, I generally want to work with experts that understand what they're doing (otherwise is probably a waste of time).