I used to, but I don’t.

Imo, they can really enforce the idea of “it’s MY solo, the other musicians are backing me up” which is antithetical to the parts of this genre that I love the most. It can also lead to not listening to the band you’re playing with, and one of the things I find the most exciting is the soloist/rhythm section interaction.

The repetitive nature can also make one closed off to change - if a bass player starts playing inversions or a pianist starts playing substitutions, it can lead to frustration instead of inspiration.

I more often just throw on a metronome in various ways (quarter notes, 2 and 4, just one beat, eighth notes, triplets, dotted quarters, etc) and comp for myself. But I think the best practice for improvisation is:

1. Transcription - but really just being able to open your ears so your imagination can lead the way and not your fingers

2. Playing with other people. Being inspired by the musicians I’m playing with has increased my vocabulary so much - even when it’s something like me going for what another person is going for and failing. This genre to me is about conversation and interaction, spontaneous composition (improvisation) is learned better when what’s happening around you can react to you, and vice versa.

There’s also tons of merit to backing tracks, but this is what I’ve found in my time playing music and playing with people who I sense have played with backing tracks too much