I tried 10 hour days *once* for a project crunch, and that was a bad decision in every regard.
If your office hours are officially 09-18, but you’re working lunchtime and until 19:00, I don’t expect that officially reducing hours is going to help, because I expect you to unofficially keep with the longer hours anyway. On that basis, I think you personally would be better off with fewer days than shorter days.
On the other hand, if you keep to the shorter hours, I think either shorter or fewer days would both be an improvement, though I don’t know which is the better quality of life.
If your office hours are officially 09-18, but you’re working lunchtime and until 19:00, I don’t expect that officially reducing hours is going to help, because I expect you to unofficially keep with the longer hours anyway. On that basis, I think you personally would be better off with fewer days than shorter days.
On the other hand, if you keep to the shorter hours, I think either shorter or fewer days would both be an improvement, though I don’t know which is the better quality of life.