[endtime]

> The ideal configuration for a problem set is a single partner who is at roughly your ability and is willing to meet earlier in the week.

I agree with everything he said, but in my experience, the part I've quoted is at least an order of magnitude more important than the rest. And don't forget the "roughly at your ability" part - if you work with someone much smarter, you may just get more confused and you certainly won't feel like you're contributing much; if you work with someone much less smart, it's a waste of time (which is not to say that helping people isn't a nice thing to do - it just won't help you complete the problem set).