That's a valid question and I'll try to give you an honest answer. It's certainly easier to boycott works of specific actors, writers, or directors, than it is producers, though I try. I have undoubtedly watched movies from Weinstein's production company without realizing, as you noted, his catalogue is enormous. Though if I'm aware of Weinstein's involvement in a project beforehand, then I try to steer clear.

I guess I boycott on a case-by-case basis. It's a lot harder to boycott full production companies than it is individuals.

That being said, there's a reason I haven't watched Chinatown despite hearing how great it is, or Shakespeare in Love, or American Beauty, etc. It's also why I lost complete interest in Harry Potter and ignored Hogwarts Legacy. And going back to Neil Gaiman, I have several of his books, comics, and enjoyed most of his film and TV adaptations, but now thinking about any of his work leaves an unpleasant taste in my mouth.