Can you study too much?

So today I was eating lunch with a few friend when I asked them what they were doing this weekend.  "Studying for finals", simultaneously from two of them.  I then asked if they wanted to hang out when they weren't studying for finals to which they replied that they wouldn't have time around their studying.

Lets do some math: if you include Friday after school my friends probably each have at least 35 waking hours in the upcoming weekend.  That is approximately a whole lot of time if you really think about it.  Now maybe I don't have the attention span that my friends do, but I reasonably can't spend more than about three hours at a time doing focused work.  I can sit at my desk for as long as I want but after about three hours nothing gets down on paper and nothing gets absorbed into my memory.

So for me, the prospect of spending an entire two days studying without any breaks for usual weekend activities sounds not only incredibly boring, but really just not a good use of my time.  It could be that my brain just doesn't work like some other peoples', but in my opinion trying to study too much in a given time is becomes ineffective after a bit and, honestly, its really just no fun.