When using the moveable anchor, I find that octaves it a little tricky. In disco basslines I understand that it's necessary to break the rules of course by anchoring on only one strings, but I find that it makes for some wonky angles. I tend to pivot on the anchored thumb, resulting in a kind of an odd looking sideways or diagonal pivoting of my wrist on my thumb. If I move my wrist directly up to reach the octave, the back of my thumb will come off the B string. What's the best technique for reaching up there?