This may be the number one difference separating adult players from kids...structuring our limited time into consistent and useful practice sessions. After all, some days can get so busy we don't realize until bed time that we skipped lunch. Because the quantity of practice time can be so limited for an adult, it's important to focus on the quality of practice time.
Regardless of when you practice or for how long, the most important aspect of practice is mindfulness. A half hour of focused practice can go a long way and is profoundly more effective than an hour of “playing through” your repertoire wondering what you’re going to have for lunch.
So even if you only have 10 minutes to spend on a one octave scale, practice that scale bringing full attention to the individual techniques required, like intonation, evenness of tone, or keeping at the sounding point.
Of course it is very difficult to have a comprehensive awareness and monitor every detail of your playing at the same time. The best practice habit is to pick an area of focus, say intonation, and create an intention before you start to play. For instance, you may say, "for this song, I am going to make sure my third fingers are in tune." Then you might say, “ok, this time through I’m going to pay attention to the amount of bow I’m using for these fast notes”. By stating your intentions before you begin to play, you are in essence drawing your awareness to specific focal points.
The beauty of practicing “awareness”, is that whatever you had been focused on will continue to manifest for the remainder of your practice, and will generally improve your level of playing much quicker than unfocused practice. So although you may shift your focus from 3rd finger intonation to the amount of bow you’re using, you will have created a subconscious awareness of your 3rd fingers.
Conscious awareness breeds unconscious awareness, which in turn breeds accuracy.
That's one of the reasons the Violin Lab lessons break down the technique and fundamentals of violin playing into such small parts. Our goal is to provide the details necessary for you to develop a keen sense of awareness when you play. There's great benefit to concentrating on and perfecting the small components that make up any skill. So our advice for the time-challenged adult goes back to that old cliche...quality, not quantity. Whatever time you can find each day, and whatever you choose to practice, be it a song or scale, make that time a dedicated, fully involved and specific period of practice.