These apps are useful to a degree however they still require the user to be very self disciplined. What I find is that the biggest problem to any student learning a new instrument, is the lack of self discipline and the inability of the parents to manage their child’s, or even their own time . The failure to put a structure in terms of scheduled practise times to stick to is the single most impacting factor on a students success or failure . It’s a real challenge and sadly no app can substitute this .