I agree with you. We should set up a limit for both money and time. Generally people focus on winning or losing money and they forget the time that is spent while gambling. Also it is good to be able to manage our emotions.
Setting up a limit when we gamble, time, money and attention that we are giving to this activity must be limited. We know where it can lead us if we aren't so careful on what it can bring to us. I was once became addicted before and learning from it this is the best practice that every gambler must.
I don't disagree with you since there are a lot of people that can't control themselves, wasting their time, money and attentions to gambling. Gambling is not really a waste of time unless you are making it one of the more reasons that you are wasting you're life.
Instead of focusing on gambling, why not focus on other things that will give you good profit in the future. I think the really best practice of gambling is to avoid gambling since it will not only waste your time of being productive, it will also waste of your money on it.