Here’s my method on how to become proficient at the violin.
One should practice everything in all 12 keys by following the key of the day. Today play patterns in A including scales, arpeggios, and melodies. Tomorrow do similar exercises in B flat. The day following that, the same in B. Move up chromatically each day. Every 12 days one will circle around on the keys and arrive where they started.
It may appear daunting. Part of the idea is to encourage daily playing. Make an effort at a single octave A scale for 10 minutes. It’s okay if one can’t do it successfully in the day (the struggle could be on something more complex as well, it’s the same idea). Give it 10 minutes of effort. Tomorrow, struggle at it on B flat for 10 minutes. Some keys are absolutely harder than others, do not give up the fight! With daily x minute effort (x could be 5), over a period of time you will pick up the scale in each key. As the scale becomes easier, start adding more difficulty with octaves, arpeggios, bowings, melodies, the list is endless!
For one thing, the method makes it easy to pick up the instrument every day knowing what you’re going to play. That alone can be an exhausting question as an “instrument practice-er”. I know I can pick up my violin and play some A patterns and melodies because it’s the key of the day. And this doesn’t have to change one’s normal practicing. I do this for about 10 or 15 minutes then get bored and do other things on the violin for 15 minutes. And voila I’ve played violin for 30 minutes that day!
I read Charlie Parker could hear a melody and play it in all 12 keys on the spot. Since learning that, I now try to approach melody and harmony as a relative concept (mod 12 for nerds), where the key sets the tonic for the relative intervals. Practicing in this daily chromatic pattern is a great way to begin connecting those dots. Practice the 4 chord into a 5, all sorts of chord progressions. Of course, of course, at first slowly and with a metronome. But then maybe really fast, just for fun!
I could give more examples here on what to play regarding scales, arpeggios, bowings, metronomes patterns, and on and on, I’ve been practicing this way since about 2020, but that would make this post a lot more boring. Part of the method is the creativity and effort to find what to play yourself. One will definitely learn some applicable music theory!
And think of those 10 minutes on the “key of the day” as 10 minutes off the phone! It’s how I know I can budget it ;).