What works for me:
- Generally two separate 2-4 hour sessions are my personal current limit. That will be reduced in the future, but for now I enjoy it and can sustain it so I do.
- Trading duration determined by setup availability / trading performance > non-trading life events (gym, dinner, doctor's appt, etc).
- If I'm trading well - I continue. I can't control when the market gives me optimum setups so I take them when they come whether that be the first or fourth hour.
- I never limit based on profit as some of my best days were hour after hour of ideal setups. *If profit euphoria will negatively affect your performance, then yes - wise to end trading for that time until the euphoria wears off.
- Will limit based on losses b/c those affect my performance negatively.
- As other posters mentioned; focus on execution / learning / performance - profit is just a way to keep score. Duration, time of day, etc. will vary based on your personal strengths / weaknesses so multiple methods correct and they will change over time as you do.