I've recently noticed that my mind starts to wander after a while of practicing (between an hour and 90 minutes). I'll be working on my routine, and at some point I just can't stay focused. I may have a hard time following sheet music, maybe start noodling. After a small break, I do a bit better again. I think it may have something to do with my routine heavily relying on printed music. I'm currently working out of a book for sight-reading, the Miles Davis omnibook, and Simandl etudes, plus scale and arpeggio exercises. Maybe all the reading tires me out mentally. I've never had this kind of problem when I used to just work on songs and rhythms, but I'm dedicated to step up my game. Adam Neely has a recorded live stream on his YT channel in which he practices scales for four or five hours straight... Geez! That must take superhuman powers of concentration. How do you cope with this problem? Is it something you have to ease yourself into, or can you recommend anything that gets you focused again? Thanks!