How bannable is high alchemy botting?

When does 2 trials count as hard evidence. Jagex doesn't do bans passed on just play time, I can back this up with the fact suiciding even exists. If they tracked play time then playing 24hrs a day for days straight would lead to a ban.
Also can anyone explain why using breaks would increased ban chance? I'm like 90% sure all bans originate from player reports.