Whether it's running through a piece in your head to see if it's memorized, or imagining different fingering options while taking a practice break, you've probably used mental imagery to supplement your physical practice at one point or another.
Research in this area suggests that mental practice can indeed enhance learning and performance beyond physical practice alone, but how do we know if we're doing it right?
A 2015 study (Debarnot et al.) identified two things that boosted the effectiveness of participants' mental practice pretty substantially. And it wasn't anything crazy that would require much time or effort. Just a couple simple tweaks that you could use to level up your mental practice this week.