In my experience, this isn't a problem depending on the place & the times you go. If there's already familiarity, you'll know if it's OK to just walk in whenever. Just don't expect their A-list provider to be available & ready, and don't be surprised if you have to wait.
If its a place where you've never been, then it is polite to call ahead, even if it's 5-10 minutes, just so they're expecting a new face walk in the door. That small nicety helps everyone relax, and we all have a better time when we're relaxed. They don't need a lot of notice.
I almost always call ahead nowadays, even if it's just a few minutes. I usually ask if they have anyone available now - a 20 second phone call that makes the whole experience better. I see many bad reviews where the guy communicates nothing, expects everything and is disappointed. I called my favorite spot the first day they closed up shop for the pandemic. That call saved me a trip up there.