I also allocate at least 1-5% of my income each month, with 5% being the maximum. Then, when I've spent it all, I won't gamble anymore. Sometimes, even that 5% budget doesn't run out because of my lucky winnings that month.
This is my way of staying responsible when gambling. If I didn't, I might spend even more and even dip into other expenses if I had a losing streak that month. I think this figure is the safest one to stick to, and it also leaves me with money to use for investments and other purposes besides gambling.
I do the same thing as you. I stop gambling when my budget runs out and don't want to add more money. If I add more money, my losses will be big but I will not have a big chance to win. Rather than see the loss become big, I prefer to limit my budget. That works well for me as I don't gamble too often now. I realize that I need to keep my money for other needs which will be more important for me. Besides that, I can manage my gambling activity so I don't play gambling many times a month.
So, in this case, we already know our limits and try our best not to exceed them. I can't deny that sometimes I even have thoughts of continuing to gamble or increasing my budget when it runs out. This kind of discipline is what we must practice, because allocating a budget will be in vain if we aren't disciplined in implementing it.
Needs must always be the priority. Sometimes I don't hesitate to stop gambling if I see my needs increasing that month. And I'll come back the next month.