I think that's how most players do it, responsible. Either they have a pre-established threshold that they don't exceed, or maybe they exceed it a little but they are able to stop, leave and come back another day with a fresh mind to try their luck.
The problem is the problem gamblers, who don't stop at the limits and end up losing much more than they should.
I think it is also important to set a time limit because as we know gambling is completely random so you could literally play for hours and at the same time you could breakeven, so even if in monetary terms you have not really lost a single dollar when it comes to the time that you have invested when you gamble the amount is not small at all, so I think it is important to also keep track of the time spent at the casino since there are several other activities that we could be doing instead.
I think that this is eliminated when we are using the online casino as mostly we play from the comfort of our home and also mostly during our free time.Personally I play when I come back from work,eat lunch,relax for one hour and then when I wake up I like to gamble for a minimum a couple of hours.This way I am not losing anything except my free time,of course it is different when you go to play to a physical casino,you dress up,take the train to go there and spend some hours there,it is only natural that you will lose something for these hours spent there.