I think working 5 days a week, 8h a day on the same topic is insane. I can't think of anything I would want to do for so many hours a day, almost every day.

For me, switching to 4 days a week was a huge improvement in my quality of life. Now I've switched to 3, and have a completely different second job 2 days a week. And two days of rest.

I love both, for different reasons, but could never go back to a full week of IT, or switch to a full week of my new job. They balance fine, but I don't think they can exist on their own.

After going through 7 different jobs in 12 years, I realize the only thing that keeps me happy is the team itself. Great team? Great job. Bad team? Bad job. Your mileage may vary, but if you're in a rut, maybe try finding a better, more humane team.

And by all means, scale back to 4 days a week. You'll have way less disposable income (especially because some costs are fixed: rent, food, health...), but you'll have more time.

Essentially, you're trading time against money. What's most valuable to you?