I agree, but I also think that C isn't as complicated as these kinds of quizzes suggest. I've been using C for over 20 years as well, and I do know most of these arcane rules, but I don't rely on that knowledge much.

I decided a long time ago that it makes no sense to trust myself and everyone who might have to maintain my code to always remember all these rules. It's a lot simpler and safer to remember a much smaller set of rules like don't mix signed and unsigned and just enable all the warnings.

One thing I do that may be controversial is to prefer fixed size types most of the time. In my opinion, the decision to use a 16, 32 or 64 bit int type is not primarily a portability or performance issue. It's a decision driven by application requirements, and I want to express these requirements as explicitly as possible in my code.