What’s best: structured or unstructured jazz practice?
An interesting discussion, for sure.
Here are my two cents:
In my experience, you need to actually be more structured in your jazz practice than when I was studying classical way back when.
Being able to use jazz vocabulary (and not just recite it but to improvise with it) requires it to be, ironically, learned very very well. You need to learn it to a much deeper level in my experience than simply reciting off a pre-written classical piece.
It’s only when you have completely learned the inside and out of a line and internalized it before you can truly improvise with it.
There’s an interesting parallel here with a legend in Greek mythology. Mnemosyne, the goddess of memory, gives birth to the Muses of creativity. In the same way, true creativity doesn’t come out of thin air but actually requires deeply learned material as a prerequisite.
It’s only through a regular routine of well-structured practice that you can deeply learn material and thus improvise confidently as a result. Note though that I do include in my practice session a period of ‘free for all’ time when anything goes (and it’s important you do this), but this is just one part of a well-balanced practice routine.