...
a) Stop trading completely after reaching a profit goal - while continuing to watch the market and/or simulator trading the rest of the session
b) Decrease size significantly after reaching a profit goal, but still trading the rest of the session. Example being if I normally trade 1 ES - I can then trade 1 MES.
c) Another alternative could be to have a peak-to-bottom drawdown rule to ensure 'green days'. For example, if I'm up 5 points - allow one more trade with a maximum risk of 3 points to ensure the day ends green. If stopped, I'm up 2 points for the day and still profitable.
...
This is a quandary many face, yes. It is a complex psychological issue which only you will be able to sort out.
There have been many days where if I stopped at my "daily profit goal", I would have missed out on even more profit had I not simply continued with a few more trades. On other days, I have given many of the gains back by NOT stopping at the daily PT.
There have been days where I if I had stopped trading after reaching the "daily loss limit", I would not have been able to dig myself out of the hole and end up in profit. But also dug myself further into the hole by continuing to trade.
And there is then all manner of variations in between such as time of day, mood, light levels, aromas, music, market PA, etc etc ad nauseum that affect your trading.
It is up to you to figure out what works for yourself, and your personality. But you've picked a hell of a time to work through these issues, because volatility these past three weeks has rarely been seen in such a concentrated time-frame. Be well and use caution!