Can't even imagine. Back when i first started out on party, i used to 16 table and i felt like my brain was ready to leak out of my nose after 8 hours or so (and this was during an era when it was correct to fold many more hands than it would be in the current environment)
EDIT: Oh, chicagojoey. I vaugely remember who he is from 2p2, though i think he became notable after i was already losing interest in poker.
I used to 30 table 180s for about a year when I was first grinding seriously. Only 5-6 hour sessions but boy did that get my brain cooking!