Many students have experienced unhelpful practicing, or as I like to call it "unpracticing." For most students, the only change they need to make is to just slow down. Slowing down can mean:
1. Taking a break from playing to think about their practice goal
2. Choosing a slower tempo so their mind can work on everything it needs to
3. Calming their mind so they can focus on the practice task
So much practice frustration melts away when the student is aware of these ways of slowing down! Realizing that things take whatever time they need to take is an important awareness not only for practicing, but for many other things in life.