Well first of all my experience is that running overnight doesn't work really good. It can't login again after the 6 hour limit thing and sometimes it fails at randoms.
I wouldn't recommend overnight. The only random that I'm sure hasn't been scripted in is the maze random. If that one hits, it is all over for your bot. So I would recommend botting only when you have the ability to look over it.
Well I guess it depends where you're botting. If you're botting in your player-owned house training magic then the chance of you getting banned is very low even though you're botting 24/7. But if you're botting 24/7 at flax picking or mining the chances of you getting banned are higher.