My General Practice Routine
I use two iPAD apps to keep track of the time I practice each day and general MIDI editing of recordings. For general practice I use Focus Plant and usually practice 90 minutes/day between the violin and piano. For MIDI creation/recording/editing of scores and recordings I use the Forest app. I also use that app for my exercise and other activities such as computer programming, reading, etc. I like to keep pure instrument practicing separate from all the other tasks.
Within each practice session I divide the sessions into 3 categories: Deep Piano practice (memorization, deep practice of pieces I have already started); New Piano Piece practice (brand new pieces, or sections I have not started yet) and Violin practice.
For some reason, ever since I started using these apps I now practice every day. Not sure why that works, but some ideas I got from the book "The Power of Habit". The apps create ringed pie charts of my tasks (see the above image for January). So, for example, if I am doing too much piano at the expense of violin, I can see that and adjust my neglected violin. Similarly, I am trying to sight read or learn new pieces every week, even if they are not completely perfected. It adds freshness to my learned pieces.