I've gone back and forth over the years on keeping a notebook. My university teacher required us to have notebooks - but she was the only one allowed to write in it! That's one extreme of keeping a notebook...
Then for a long time (years), I just kept track of my time in a notebook. No actual notes, just how long I practiced on each piece or technique or whatever. When I moved to using an app I stopped that - the app, of course, is much better at keeping track of time.
But at the end of October I signed up for a 90 day intensive coaching program at Tonebase. I am a Tonebase member. So I picked a new piece (Grieg's Wedding Day) and the coach (Noah Hardaway) has been leading me through it. They use a web-based system called Notion for the student to write whatever they want everyday and answer questions about progress and so forth at the end of each week. Video checkins and so forth. So the Notion app is like an online notebook. It was very helpful. I knew the teacher was going to look at what I had written. I wrote about what I found in the piece, problems I found, solutions I worked out, and so forth. After a couple of months I had it memorized and was down to the slog of actually trying to stitch it all together, so I fell back on my old habit of not actually writing much down. The online log was very useful when I knew the teacher was going to read it.
I do keep a notebook of long range goals - pieces I am planning to learn to play for recitals and the dates and so forth - but that is not a daily log.
