A few years ago, I remember asking a well known modern day guitarist what he was working on. I was expecting him to talk of advanced harmonic devices or complex time signatures, but instead he told me he was working out of the Charlie Parker Omnibook.
When Dave Holland was first putting his band together he saturated his listening with Dixieland music from the 1920’s. His goal was to was to recreate that vibe in a modern small group context.

I find all great artists from time to time feel a need to “go back” and draw inspiration from the past masters. One of my favourite art museums is the Vincent Van Gogh museum in Amsterdam. A beautiful and extensive collection of his works laid out chronologically. In the middle of the exhibit while Van Gogh is at the height of his artistic output one stumbles upon these large Renaissance-like paintings. While clearly having found his voice as an artist, Van Gogh felt the need to go back and copy (transcribe) such artists as Rembrandt.
I found a similar example at a Picasso exhibit recently. Again at the peak of his cubist period, his sketchbooks at the time reveal he was still sketching nudes and fruit baskets.
That’s what is known as ’keeping up the chops’!!