I played semi-professionally for a few years and put myself through grad school with poker winnings. Thinking about things in terms of returns for any individual session is meaningless, it's always and only about your longterm win rate, your expected return. Variance is so much higher than anyone thinks, rendering short and medium term results meaningless.

Some of the softest games I've ever played in, I was crushed in terms of actual results. Poor aggressive players especially really crank up the variance. But I'd play in them again any time the opportunity presented itself, because my expected return from those games was so high.

The key for most people is to learn to not let the money affect your play, which usually means playing at stakes you are comfortable with, but not too comfortable, and quitting if an especially good or bad night has you playing recklessly. I was never quite as psychologically strong as some other players I knew, so I would play most days continually buying in to the tables for random amounts so I never knew if I was up or down for the day across my tables (well, sometimes I knew, you can tell how you are running overall). I generally allowed myself to check my balances and my stats every 2k hands or so. Other than that I was just reviewing hands and opponents, never return.