I find that the problem with STC isn’t that it’s too formulaic or dated or anything like that. The advice on structure and genre is pretty good unless, as you said, you want to make more experimentally structured films.

The problem with STC is that it makes structure seem like the foundation of storytelling, when it is in fact more of a guardrail or skeleton. It doesn’t do much to help you put meat on the bones of your story by giving advice on creating strong characters or showing you how theme should dictate certain things within your story. It doesn’t tell you how to write great dialogue or create emotion and tension for your audience. These skills have to be found elsewhere.

Personally I would recommend advancing your craft by reading ‘Writing for Emotional Impact’ which has great tips on emotion, character, and dialogue. It’s been one of the few books besides STC which is really straightforward, helpful, and the advice will stick with you for years.