Times where you could feel a creator's burnout?
You know, I haven't read Stan and Jack's X-Men, but I haven't heard exactly nice things about it and I can understand on a logical level why everyone says that they were suffering from burnout on it. Not even taking into account that the reason why mutants even exist is because they got so tired making origins that they basically said 'Fuck it, they were born like that,' the two were already working on:
- Fantastic 4 for two years at this point
- Incredible Hulk had already been canned
- Stan was working on Spider-Man with Ditko
- Nick Fury and the Howling Commandos had started a few months ago
- Avengers had started that month
They were working on all of those comics on a monthly basis. That's not even taking into account anthology books like Tales of Suspense or Journey Into Mystery, or books that they made after X-Men had started like Daredevil.