1/2 Texas Holdem no limit poker. How much should I buy in for? Bankroll?

I play 1/2 recreationally. Cash game, profiting on average about $30-$45 an hour, (around 50-60 hours a year).

I usually buy in for about $100-120. (Max buy in is 200 or Max stack at the table). -playing super nitty. Never playing with the same people. Mostly recreational players.

I feel like buying in for less than the maximum gives me a higher EV, ( likeliness to win over time) without putting as much to risk.

I mean so far it's worked for me, that being said, I don't really manage a "bankroll" which Im told should be around 20x what you're buying in for.. (-But I'm just playing for fun. I don't really care about the money.)

That being said. -Is that the secret to the sauce? - I'm just lucky, - or is this a situation of, "If it ain't broke don't fix it?"