I concur. In the beginning I used dynamic difficulty because it helps you learn to play the guitar, which is what I wanted to focus on. Now that my hands know what they are doing, Max difficulty is the way to go, otherwise you are only seeing part of the song, which then makes you have to learn a part multiple times (granted each additional time shouldn't take as long to learn as the initial couple levels but it still seems inefficient time wise). I think the best way to learn a song is to do as abteen suggested or find tab of the song you wish to learn and run through a section of the song a couple times, then play it from memory. It will cause you to memorize it faster because rather than RS's easy sight reading holding your hand, your brain has to actually do work. But everyone is different, experiment with each way and use what works best for you :)