It's a quirky show because virtually everyone is an antihero, or at least deeply flawed. Richie was a really annoying character until he "got it" then he was a slightly less annoying character. But I agree with you the notion that a week under demanding circumstances would cause a complete reformation of a character is a little bit of a push.
The Jaime Lee Curtis episodes were, in my opinion, absolutely riveting. It's probably the best acting she's ever done. They definitely aren't feel good and the "seven fishes" dinner in particular, left me staring at the screen thinking "what the heck was that" but in a good way. They were very powerful.
I did like the bit at the end of season 3, where Carmie confronts the chef that tormented him and really developed him as a perfectionist. He views that chef as his nemesis, with this huge negative emotional connection, only to find out that to the chef, Carmen was just another guy. Again a powerful moment.
I do wonder how they're going to be able to keep up the energy and narratives. I'll definitely give it a watch eventually. They built up enough goodwill with me that even if the last season drags, I'll stick with it.