I time my practice time and devote between 5 minutes to an hour to a particular task. I write down what I do. I found that I was practicing too many separate things a day, so I have decided to do only a few things a day, and at least one for a longer time. 5 minutes is a long time for a short piece I already know. I can work on specific things or play through it 5 times. 60 minutes is a long time for studying a piece of three pages. I can work on every specific phrase or on the whole.
It is interesting to look at the word practice.
It can mean rehearsing or repeating to learn something, like practicing an instrument.
It can be a habit or habitual method.
It can be someone's meditation practice.
Or the professional practice of an attorney or physician.
It can be doing something as opposed to theorizing about it.
What all this has in common is in doing something. A practice is always an activity.