BB/hour question

[Chazbot2000]

I've heard a bunch of "rules of thumb" re: how many big bets a decent player should win per hour, but no definitive logic behind those rules of thumb. Could someone help me understand this?

Generally I hear either:

One big bet per hour for live play, or:

Two big bets per 100 hands for online.

I would think at lower limits, there must be a way to average well above this (maybe closer to 3 big bets) as the fish could be totally outmatched. Am I off base in thinking this is possible on a consistent basis?

Thanks in advance for the advice.