The paradox of practice
I find that having a regular practice routine has both advantages and disadvantages. The advantage, of course, is that my technique, fluency and knowledge all improve over time. This is important. Without making some progress in what I'm able to play, I tend to stagnate in what I do play.
When I practice I like to work on chord voicings, fingerings, voice leading, and occasionally scales and rhythmic motifs. I also try to advance my comprehension of theory and terminology. I've been doing this for the past nine years since I started playing guitar after a two-decade layoff. The practice routine has paid off. I'm playing things now that I never would have imagined nine years ago.
But since this article is about the paradox of practice, here's the rub... The things I learn in my practice sessions actually make my playing worse for a while. It takes time to integrate new techniques into my playing, most of which is improvisational. I tend to play instinctively and enjoy taking chances with how I play during an improv session. The problem is that the new material and techniques have not yet become instinctive; there's a bit of a "gear shift" necessary to use something that I've practiced in the context of an improv session. After a while the new material becomes instinctive, but it takes time to "feel" the proper context in which to introduce a new idea.
If I practice less, I tend to draw from the same set of ideas all of the time and my musical progress stagnates. But I play with more confidence because the material has had a chance to become part of my intuitive repertoire. Damned if you do, damned if you don't...
For years I had noticed that my playing improves incrementally. I'd have "breakthoughs" or "aha!" moments when least expected, followed by long "plateaus" where nothing changes or improves. As I began to practice with greater deliberation I noticed a corresponding improvement in my ability to execute. That alone was not enough to develop as a musician in the ways that I had intended.
There was still the issue of me not being able to imagine new material. Listening to other people takes one only so far. I know plenty of players who can play convincingly "in the style of" some other player, borrowing liberally - often literally - from the recorded catalog of some other musician's output. This seems to become a self-limiting process for many players. They develop a certain facility in a particular style and are loathe to break out of their comfort zone and explore something from a different genre or school of thought.
To counter this tendency in my own playing I try to set aside some time to deliberately break away from all the things I've studied and practiced. Musical performance depends upon muscle memory and habit. Breaking habits is difficult. One thing I've found helpful is to literally "grab" a handful of notes on the neck of the guitar using an unfamiliar or even uncomfortable grip, just to hear what happens. Surprisingly often this kind of exploration leads to an interesting exploration. I still have to step back into "analyze and repeat" mode in order to retain the new ideas. Sometimes I'll add a minute or so of a recorded example to my musical "scratchpad" journal.