Thanks for your question.
First, I never meant the scales in the practice sessions to “stick”. Think of it more like going to an exercise class. In this case, just doing the scales is activating your mind, working your fingers and training your ear.
Second, which scales should you learn? Good question. This may sound blasphemous but you could play beautiful guitar without ever learning any scales in this respect. That said… I would encourage you to learn scales and there’s much more to this. I’ve created an entire lesson on this question (and I could write an entire book).
BTW… I practice scales every day as a warm-up. I start slow and build up speed. I either choose ones that I want to improve on or ones that I’m going to use later in my practice. For example… recently I’ve been composing a song that is in the key of A minor. I warm-up with several versions of the minor and Flamenco scale in A.
There’s more about this in the lesson above. I’m sure you’ll find it helpful… and possibly bring up more questions 🙂