I think it's ironic that cigarettes and alcohol are legal and abundant but marijuana is illegal and taboo.
Weed is great. It has many well-documented benefits, and can really help any bodybuilder -- especially beginners. The muscle relaxation, deep sleeps, increased appetite, increased blood flow, etc. I made some of my best muscle gains when smoking shit tons of weed.
The downside is if you don't balance it with regular cardio then you're lungs will take a hit. Also, if you smoke too much too often you'll find your focus and motivation waning a bit.
Just keep everything balanced. I quit all the time for a month at a time then do it once a week for a while, etc...I'm leaning towards less right now because I'm heavy into a volume program while training for a half marathon, and I need my cardio system in top shape. Otherwise, I think if you train regularly and hard, perform regular cardio, eat a balanced diet with good macros, and feel confident in your lifting and see regular results then once a week for weed is absolutely no problem at all, and even beneficial.
It's better for you than drinking is. The only benefits from drinking are maybe some social benefits. Otherwise, weed is dirt cheap (alcohol and associated costs like cover charge, cabs, etc) can be $40-100/night, whereas weed is like $5-10 for a night. Plus, weed has so many health benefits.