When I am bored and have the extra BTC or cash available, I will play about 4 hours in any given day. Because of my limits to funding, I can not play as much as I would like to. When I get into the dice though, I always seem to want to play more and more. I have a hard time stopping!
Playing 4 hours is already too long. You can accomplish a lot already with that amount of time. And what do you get from that? I am guessing, mostly nothing. Most of the time, the house wins especially if you play too long. So those 4 hours are wasted time. I think you need to get a new hobby that is worthwhile than just spinning dice. You can get addicted too.
That is a lot of time to consume in gambling alone, if you aim to enjoy and win money at the same time, I think 30 minutes would be enough for you. Because the longer you play the more you are prone to being addicted in gambling and that is not good as you could have spend your time in a productive manner.