Me too !
have worked out that bad days are normally when I am distracted or under pressure.

For a good day it helps me If I get my music head on and plan out what I want to do and practice it away from the instrument. Maybe on a walk; then when I get started it has a better chance of going well.
doing enough reps to get bored and let go has on occasion resulted in sudden steps forward.

Keep at it. no rush have fun