With my company, I work on a project week system. Projects are assigned on Monday and due no later than Friday at 5pm. You work at your own pace until you're finished, and are paid by the project, not the hour. If you're done by Wednesday, then you can turn it in and take the rest of the week off, or start another project to boost your earnings.
When we used to do the traditional "40 hour work week"; productivity was no where near what it is now, and scheduling was a nightmare. Now, scheduling is a breeze because there are only a couple people who still have "traditional hours". People are motivated to actually "work" when they're at work now, and things have never run better, I'd never go back.