Not a good idea, I tell you. Either you end up completely devoid of energy after doing everything, or you'll miss some and feel miserable. I vote for the latter.
Besides, there are too many unforeseen tasks you end up doing that you might not have time for the important things.
My solution? one task, an important one. I have to get it done before the timeframe ends, no matter what. If it happens before the scheduled time, I pick up another one. If I don't finish it before the stipulated time, I try to find out why things transpired that way, and how to avoid it in the future.