In his excellent book [1], Andy Hunt explains what expertise is with a multi-level model [2], where a novice needs rules that describe what to do (to get started) while an expert chooses patterns according to his goal.

So, "best practices" are patterns that work in most situations, and an expert can adapt to several (and new) situations.

[1] https://pragprog.com/book/ahptl/pragmatic-thinking-and-learn...

[2] https://en.wikipedia.org/wiki/Dreyfus_model_of_skill_acquisi...