In my mind there are three components.
Practice
Training
Playing
Practice - stroke development, eyepatterns, speed control, cueball control
Training - playing the ghost, working on specific shots that are troublesome, i.e working those elements that need refinement based upon the needs of the player.
Playing - Playing the game is the culmination of practice and training, the results of which are used for further practice and training sessions.
Relying on getting your practice in while playing, restricts the player to get the types of repetitions required to make a change in their game.
This was my point with the war analogy, when you play top flight players ONE mistake is enough for you to be sitting down for the rest of the set. At that point you need to learn by observation.
I think this pretty well sums it up. If you are playing with a decent player, you aren't gettting much "practice or training" when you are sitting in the chair.
Practice and training are not to be confused with playing. They are completely seperate.
Practice and training are where you do some drills, get a preshot routine, work on areas of weakness, get a solid foundation on basic fundamentals, and countless other thing. Yes drills get boring fast, so only do them for 10 to 15 minutes, then move on to something else. If you are bored, you aren't getting anything out of it. Keep it interesting. Oh, drills should be "measureable", so you can track your progress.
Playing is applying all of the things you learned and the skills you aquired while practicing and training.
Baseball, basketball, football, and most all other sports, they go to training camp, they practice to hone their skills, and then they play games to try and win, and pool is no different.
There is a lot you can learn from a better player, and I'm not taking anything away from that, as they can teach you a ton. But you have to put in the table time for training and practicing if you really want to exceed.