I watched a lot of videos made by technicians and did a lot of reading. It doesn't take too long to study enough to get the basic certification, but that is not the whole story. I have done lots of electronic prototyping and test system creation, copper plumbing, etc., so I felt comfortable with tools and electro-mechanical systems. If your entire career has been behind a keyboard, you have a lot more than an hour of studying ahead of you.

Correct me if I'm wrong but I think 80% of it boils down to "do not release refrigerant gas into the atmosphere"

The test (and studying for the test) does not cover how to do repairs or fix HVACs. I learned that elsewhere.