In the book ‘deliberate’ practice isn’t described that way really, more of a general process where the person doing the practice does so in a way where they focus on working on their weaknesses and working towards specific goals. He takes the 10,000 hours ‘rule’ and says it’s not the mileage really as much as what you do during that time. (Anders is the one who came up with the 10,000 hours thing originally but it was popularized by Malcolm Gladwell )
Watching the Oz Noy interview the other day I was struck by a similar idea when he talked about practicing scales, he said he doesn’t like to just run up and down them in a typical way but instead tries to concentrate on finding different ways to play them that increase his fluidity on the neck (that example he played of playing a major scale ‘diagonally’ was pretty neat and something I’d never have considered a practical way of playing that scale - I really admire his ability to find something like that and stick to it until he had it fluid, I get the feeling if I had found that even by accident I probably would have discounted it as a not very practical way to play that scale).
Another book I’m reading at the moment is ‘the Inner Game of Music’ which is pretty interesting, in that he discusses cultivating ‘awareness’ while practicing, so in a particular session you might focus say on tone, or dynamics, or simply monitoring how much stress you are holding in your body as you play. The idea being that if you tune in enough to your own internal feedback you can make better progress on an instrument. A lot of that book discusses the intuitive verses analytic approach (he’s much more in favor of the former!) but says that you need to train yourself to pick up on those intuitions, by working on your focus and deliberately giving your analytic side ‘jobs’ to do (like measuring muscle tension etc) so that it gets out of your way and lets your intuitive side work better.
Again I feel in both those examples, playing guitar while doing something else is less likely to lead to that kind of practice.