If you bot <24/7 you'll get less gold/day for sure. On the other side NOTHING can guarantee you that you won't get banned if you bot 12 hours per day. I've had bots banned and still have some that have 800h botted and still going strong, and there have been no rules about how many hours you should bot.
For me, it's pretty damn simple, buy bots, level them by hand because blizz bans leveling bots fast as hell, and then just let them farm 24/7, they will pay themselves in couple of days and then rest of it's profit.