Yeah, proper dosing of cannabis is tricky. I think used sparingly and in small doses it can be helpful for many creative practices. It is very easy to take too much or use it too often because the feeling of being high can be so pleasurable (except when you get paranoid and it's the absolute worst). It also can make you feel very inflated, which is a great feeling in the moment, but kind of embarrassing when you look back at the reduced quality of what you actually produce when high. Still, I think there is value in it since I have had useful insights while high that motivated me when I sobered up and was better able to execute on my inflated ambitions.

Alcohol, on the other hand, I have really not found especially helpful for creativity. YMMV.