Next time you have the glass off one of your pins play it and catch the ball before drains and place it back on the flipper to see what it takes to make that shot that seems impossible. For instance it is easier for me to hold the ball on the inside of the right flipper on Dialed In and then slowly release the ball but almost instantly gently flip it into the cell phone. Practice these over and over again till you can achieve that shot almost every time and by doing it with the glass off you don't have to wait till the ball reloads every time and by doing that and also like finding a better way to obtain sim cards and I bet the that nobody could beat you on your own machines. Ball control to me is what makes an average player a top playing and try to keep the ball speed down and 2nd to that would be nudging the keep the ball from draining either in the middle or on side exits.

She can do the recovery skills after putting the glass back on but just practice difficult shots when she takes the glass off for something else like when doing maintenance like waxing etc. Not asking her to always play with the glass off. Point is to speed up practicing.