Optimal session length for a cash game player to play his "A" game?

[GRIN281289]

for me, the best time to play poker 2-3 hours and then I also lose . now slightly longer than the 3-4 hours of the game . worked on the bugs

 

[Ragequit]

It's different with each person. But I work in 2 hour blocks. With a 30 min break after every 90 mins. Otherwise I get tired and start losing.