It's quite interesting to see the effort you're putting in. Instead of trying to cut back little by little, you're actually cutting off everything related to gambling, preventing you from accessing it altogether.
We only know what works for us. Maybe he also tried cutting it little by little but he still finds himself losing more, so he just decided to cut it all. For me, I have tried cutting it all but I noticed that I feel bad, so I decided to just cut it slowly and I think I'm doing well this way. Even if his desire comes back let say, there is still no way for him to play again because he already blocked all the gambling sites. Time will come that he will not think of gambling anymore. So we can say that his method is truly effective for him.
The portion is obviously different when we do it slowly and do it immediately so in this context it obviously depends on readiness.
If we are not really ready for the risk then cutting directly will only make you less comfortable and even more depressed so seeing such considerations is definitely better than doing it directly.
But on the other hand what the OP did was also very good, but when you have decided to cut directly then there must be a truly sincere intention to stop because after all once it is done then the conflict is not with gambling directly but with ambition, emotion and passion for gambling in ourselves and of course this is clearly not an easy thing to do.
Everything depends on your choice in the end because after all, before doing something, we already have our limits and obviously things like this have been thought of with some consideration.