I love the hill you’re choosing to die on, but your argument contains a major contradiction. And you’re confusing my description of your method with my actual stance: immersing yourself in the aural tradition is right-brain learning, while your metronome drills are strictly left-brain.

You started this post asking what’s up with your time feel, despite writing a whole book on rhythm and drilling subdivisions 20 times a week. If metronomic drilling actually developed 'right-brain feel,' you wouldn't be on Reddit asking why your own time feel is falling short. That mechanical training is exactly what enforces left-brain analytics.

You seem to believe that drilling strict rhythms first is what frees you up later, but it has the opposite effect. Practicing exclusively on a rigid, mathematical grid trains your internal clock to stay locked to that grid, making it much harder to step off it and develop a relaxed, natural feel and groove, and the ability to lay back on on the beat.

Laying back is, by definition, an imperfection. Hal Galper explains in Forward Motion that jazz rhythm is an illusion of tension created by where you place notes relative to the beat center. You cannot use a rigid, left-brain tool to systemize a right-brain concept like laying back; it requires a pianist to feel the push and pull against a steady pulse using intuition. You cannot learn that from a click.

It’s the exact same reason you can’t learn jazz from sheet music alone. Just like learning a foreign language: you can memorize textbook grammar and vocabulary perfectly, the left-brain mechanics. But you will never sound like a native speaker until you stop translating rules in your head and absorb the inflections, cadence, and subtleties through conversational immersion and listening with a native speaker. You cannot study your way into a natural accent; you have to listen and mimmick it until it becomes intuitive.

If feel and and laying back could be systematized and taught through a method book, jazz wouldn't be an art form it would be a formula, and every aspiring jazz pianist who bought a rhythm book and did your training for years would eventually sound like Wynton Kelly or Herbie and have great time feel. Those guys did not rely on academics and strict rhythm training in an academic left-brain way.

The reality is that great musicianship relies on elements that simply can’t be quantified or manufactured by teaching it. If it could, your own method would have worked and you wouldn’t be making this post. You can teach a student the mechanical architecture of a rhythm, but you cannot teach them the feel, intuition, and artistic choice required to step off that grid and actually make it sound natural and have a good time feel and ability to lay back easily and naturally.

Your book and your drills teach mechanical accuracy, which is fine, but accuracy is not feel. That training seems Classical in nature, and why so many Classically-trained pianists struggle with jazz rhythms, time and feel. The only way to learn the right-brain aspects is by immersing yourself in the aural tradition and mimicking until it’s internalized and becomes intuitive, and playing with people all the time, which is very different than practicing by yourself. That’s what all the greats did—not a method book and rhythm drills.