Keeper's explanation of 31 hours is why I do it.  Someone mentioned it once at WT:AIV and it seemed like a good idea.  I wouldn't block a 3RR violation for 31 hours because, what I'm basically implying with a 31 hour block is "I don't expect you to be productive tomorrow, either, you punk", whereas with a typical 3RR block we hope/expect/pretend to expect them to have cooled down and not resume edit warring immediately. 

 And Keeper, the slight pain you felt was just me psychically hitting you with my mind.  Trust me, if I were to hit you for real, it would definitely feel more like an 11 or 12 year old girl hitting you.