I think memorization is a useful practice technique, even if you don’t intend to perform “from memory.” Memorization of music has several facets:
- Aural memory: I should be able to sing the music (at least in my mind) from beginning to end with confidence and accuracy.
- Content/visual/analytical memory: I should be able to more or less transcribe or describe the music from memory. This might include being able to picture the printed music, being able to describe it in reasonably specific terms (“then there’s a fast run up a C minor scale, ending on a long high F with a fermata”), and/or being able to discuss the formal and phrase structures. (I don’t think you necessarily need to be able to think in terms of formal classical music theory, as long as you have some kind of vocabulary for talking about music.)
- Physical/muscle memory: If I have practiced in a thorough, detailed way, I should be able to more or less play on “autopilot.” I don’t want to perform in a disengaged way, but I do want to be able to focus my mind on non-technical things.
The benefits of memorization, even for not-strictly-from-memory performance, include:
- Confidence born from deep mastery of the music.
- The ability to handle minor on-stage crises, like a missed page turn or a sudden distraction, with ease and grace.
- Internalization of the music in such a way that interpretation becomes natural, expressive, and personal.
- Freedom from “reading” issues. Sometimes musical passages are made difficult by visual factors, like hard-to-read notation, a personal reading difficulty (such as dyslexia or poor eyesight, perhaps), or something that simply doesn’t “click” visually for the reader. If looking at the page is causing problems, then just don’t look.
- Ability to take a step back from the page, literally and figuratively, which encourages greater connection with collaborators and audiences.
If you are already practicing in a thorough and deliberate way, you are probably well on your way to memorization already without any extra effort. Use good practice techniques and memorization together to support better preparation and performance.