The reality is if you bot 24/7 and get reported and any GM looks into it, how do you think it would look? Noone can run an account 24/7 for more than 2 days no matter how much Red Bull you drank. To bot for 24/7, IMHO it's not a matter of IF, but WHEN you'd be banned. All it would take is one slip and any GM looking into it would see your time online and suddenly that 24/7 account goes to 0/7.
In my opinion, bot reasonable amounts of time - if you want to bot 24/7, do it on 2-3 different accounts so none of them are more then 8-12 hours a day (and still monitor them of course). Sooner or later, our bots going to do something that gets him/her reported - running into something for 30 minutes, dying and running into the same elite mobs 20 times in a row, flying up from a mine node and getting stuck in a tree and trying to use the 'unstuck routine' over and over... there are a number of ways - it only takes 1 at the wrong time. When it happens, you want to make it so it's not obvious that you're botting.