Is it recommended to play for a certain number of hands or amount of time or do most people just play until they are up a buy-in or two (2NL)?

I'm not really good at playing deep, so when I find myself up 3+ buy-ins (spread between 4-6 tables), after only 150-200 hands, I usually stack off with 1 or 2 (donking or getting rivered) and then try to quit while I'm still up for the session. I learned the hard way that if you end every session when you are down, your bankroll ebbs away. DUH.

Also, it seems that people play differently against you when you are 200BB+ deep. So I have been ratholing/table hopping. I don't have any stats, but I feel like it's a lot easier to get a fish on with 100BB than with 200BB+. It's like they avoid you, since you're obviously 'good enough' to get deep. I think my winrate goes down when I'm deep.

Are there advantages to being deep that should outweigh the disadvantage of a reduced winrate? Or should I just keep ratholing and quitting while I'm ahead?