Another poster claimed that he has been running 24/7 on multiple bots for 2 months with no ban. Personally, I don't see a reason not to. I think shutting down your router/modem/computer for at least a couple hours every other day or so would make it a lot more legit. However, as other people have said, you can stay logged in and afk in Diablo III indefinitely (until patch day) so Blizzard has no reason to expect you to log out of the game to sleep. Maybe you need Diablo III as a night light, maybe when you wake up from a nightmare you need to take a look at your big strong handsome barb to calm you down. Maybe you run on the uberman sleep schedule and get 2 total hours of sleep per day.
How the fuck would Blizzard be able to verify any of that? I believe your chance of getting banned botting 1 hour a day is not very far from your chance of getting banned botting 24 hours a day.