play every day if you can, even if it's only a few minutes....
IMO...the above is the key (no pun intended) to improving on any instrument.
Especially for the stringed as they require much finger toughening.
When I was giving guitar lessons that is what I drilled into their enthusiastic minds.
I also emphasized that one needs to practice in between lessons, without fail, as that is where the improvement will occur.
That's my take on it....