Guess I must be wired differently, but I look at that extra time and think “what more could I do?”, rather than “I’m convinced this is the output required of me, thus I will do no more with my new found time.” shrug
Everything you produce once you are punchy, you will have to re-do tomorrow morning during your productive hours, at which point you have to keep working later to get done what you had planned for today, and now you're in a never-ending loop of reworking your code.