Comment by smartaz42
I've found Jason Ricci to be a most useful source as well. Adam Gussow, Tom Leckie, Will Wilde, and Howard Levy all have recommended YouTube content.
I haven't checked out the app, but certainly plan to in order to fine tune my scales (major/minor penatonic, blues, and a few more).
By the way, once you get 2nd position major pentatonic those same notes are 5th position minor penatonic (albeit with a different starting notes). Same for 1st major and 4th minor, and 12 major and 3rd minor.
Glad to hear you're planning to check out the app! It includes scale training for major, minor pentatonic, blues, and a few more. If you notice any scales missing that you'd like to see added, feel free to reach out — I'm always happy to improve it based on feedback.