The ideal minimum when learning new skills is 1/2 an hour a day. The first ten minutes should be spent revising last weeks practice, mostly techniques. This could be bending and some chugs, for example. Then the next 20 minutes should be spent on learning something new, practicing it and/or revising the most recent lesson you are up to. If you have an extra ten minutes then I would use this to have fun, playing anything that comes to mind, or trying new ideas over the lesson 4 jam track. I hope that helps?
If you have less than the 1/2 a day then you can break this down in ratio, the main thing is to practice everyday even for ten minutes if you can!! 🙂