Uhh... duh. You gain so much time.
It takes the simplest math. The average school year consists of about 35 weeks, with half an hour less every week, and about two hours on quarterly occasions. This adds to about 25 hours less, at the most. With an entire day off (about seven hours) every week, that's 245 hours off. It's so obvious that I just did that math for fun.
You can do so much more unproductive crap with more time and not feel a guilty.
Instead of getting out early every once in a blue moon you have EVERY Friday off