I usually play for about 1-2 hours cumulatively a day. I play a lot walking across campus to my classes, mostly just fooling around with string tricks and such. On weekends though I probably do 3-ish hour sessions.
on average i like to try and play between 1 and 2 hours a day, though the majority of that is simply practice tricks I've written up to stay honed. i find i can burn out sometimes so i try to have one day a week when i don't play kendama and focus on something else. i think this is necessary for the longevity of playing kendama. my reasoning is simple, those events when you play for every minute of the time you are there really wear you out, i think rest is good for everyone sometimes even if its something you love.