I'm getting the feeling that the author wanted to run the joke on black-companies to a higher, comedic level, with all the survival training, and being scarier than Yakuza, etc.
But it also feels like the MC is praising his abusers, by reciting their motivational speeches, and constantly going: "I got lots of training from my previous work place!" (with a smile)
I get that it's supposed to be a joke, but it sure feels like propaganda at this point. I'm sure it's not fun for Jap youths to constantly see how bleak and terrible their future employment is going to be, and you might end up praising them for it.
I'm taking it way too seriously, obviously, but this manga just rubbed me the wrong way somehow.