I'm a professional sculptress who makes math and physics visualizations, weed is indispensable to my creative process for exactly the reasons you described. It helps me get into that state of flow faster, helps me better visualize abstract concepts and figure out how to translate them into physical objects, makes the boring repetitive parts more fun, and it helps me find more novel and interesting solutions to different construction problems I encounter. I never get stoned, just buzzed, because if I get stoned then I can't do anything. And I really only smoke when I'm sitting down to get to work, I'm not much of a recreational smoker at all. Weed is for business hours! If I just wanna have fun, I'm gonna drink beer.
Alcohol has a pretty negative effect on my work, though. I get sloppy and it's a terrible idea to play with sharp objects and permanent inks if you've been drinking anyway. Loosening up and being unafraid to make things I think might fail isn't something I really struggle with because my creative process is super iterative and experimental. That one Ira Glass quote made me realize the power of full-on wallowing in and relishing the ugly prototype stages of things, so I do a lot of that knowing that after a few different versions to work out the kinks and try some different approaches, I'll have something really good on my hands. I love putting a final sculpture beside the ugly prototype it began as and seeing how far it evolved, it's like looking at a baby picture beside a picture of the successful, well-adjusted adult the baby grew up to be. I can't help but take pride in both of them!