Hey, that is the method that I always recommend. But, I prefer to call it the cycle. Though, it is layed out in a circle in the graphical sense (on paper). After you go through it, you will tend to see the cycle in which all melodic movement follows (pop, jazz, hiphop, blues... Everything).
Anyway, I would just learn the crap out of the major scale. All scales in western music are derived from this scale. And, most foreign scales are used within the context of the major scale to simplify things. Learn the major scale and cycle it through the cycle of 5th/4ths. After that, throw in the modes. And, learn to differenciate between the different minors (aeolian, melodic and harmonic). Sure, you can throw in the pentatonic, chromatic and whole-tone scale, as well. But, the mastery of scales (any scale) starts with the mastery of the major scale. So, if there are any scales to learn by heart, there is only one. The major scale. Everything else is just an alteration to the major scale (in western music).
But, I have one major (no pun) recommendation. Do not think that you have to remember every single note of every scale. That will come with time. What you should really focus on is interval relationships and patterns. The mind can only take in so much at a time. So, first focus on the patterns of each major scale in each key. Then, after you have that down, focus on the interval relationships. I don't mean just listen to the differences. Really listen to them and let them create a particular color or mood within you. Associate them with something. Whatever it takes to know the difference in sound between a 4th and a 7th and so on. After you got that down, start to learn the aeolian minor. Aeolian (natural) is the easiest as it falls within the major scale, it is just another key. This is your relative minor. All major scales have a relative minor that is made up of the same notes. All the relative minor is is playing the major scale, but starting from the 6th interval. The sixth interval is also called the Aeolian mode. Thus, Aeolian minor (the minor that falls naturally within the major scale). Once you understance the relative relationship between a major scale and it respective aeolian minor, venture onto the other modes (dorian, phrygian, Lydian, Mixolydian, Locrean, (Aeolian) and Ionian (which is nothing more than the root in a diatonic scale). Then, once you have the modal relationships understood, move onto the other minors (melodic and harmonic). Then, by that time, your mind should be quite curious about what else the world of musical knowledge has to offer.
Sure, you can just play whatever comes to you. But, it helps to have that toolset that allows those things to come to you naturally. And, that is what practicing this stuff is all about. That way, you are able to translate what is in your head into actual sound without even struggling. You just play it as it comes to your mind... And, it is dead-on accurate. Your fingers learn to translate what is in your mind to the medium of an instrument with razor sharp accuracy and speed.
But... And that is a big but. For every one person that has that natural talent to mesmerize the public without any formal practice or training at all, there are millions that have to work to refine that talent within them. They have to work and practice to achive what a very select few can do naturally. That is just the nature of it. But, always remember. No matter how much you know or how much you have learned. That is no replacement for creativety. Because creativety is what really makes the public point their eyes at you. So, do not ever be afraid to just let go and experiment with whatever knowledge you already have. That is what the best songs have come from. Just pure "unthinking" brainstorming. You can have all of the musical knowledge in the owrld. But, without a true talent for creativity, you will be playing music for yourself for the rest of your life.
