It's quite the oxymoron, isn't it? But if I had a dollar every time I've asked a student who was struggling with a difficult passage, "Have you done slow practise here?", I would be sipping cocktails on a tropical beach* somewhere by now.
With piano, as with any form of activity that requires repetitive fine motor action, one of the main points of slow practise is to refine the muscle memory. Now I'm no neurologist, but when you are working on slow practise for muscle memory, there's a lot going on. Your brain is forming synapses, connecting the movements between smaller muscles groups, and memorising the shapes and feeling of bigger bodily movements. That's a lot for any brain to work through, and if a student tries to rush the process in order to learn the piece quicker, they are actually going to take longer to reach competency than if they just slowed down.
When a student comes to their lesson and can almost play what we've been working on, they will get to that point in the piece, fluff their way through it or play it at a different speed to the rest of the piece, and then nine times out of ten will tell me "I did practise this part, I just can't get it!" My first port of call will be to isolate that bar or section of bars, and drop the tempo to maybe half of that which they were playing so that I can diagnose the issue.
One benefit of slow practise is that it highlights where technique might be being quietly and unintentionally neglected. A tricky bar played at pace can often mask technical inaccuracies, sweeping things under the rug so to speak, but if it is slowed down and played at a fraction of the tempo, incorrect technique or inconsistent fingering will be brought to the surface.
This form of practise I will admit is not always fun, which is probably why students don't automatically go to it as a remedy first-off. It requires a mindful approach. It needs absolute engagement in the process and an awareness of which section of the piece to isolate. It needs a student to have good awareness of the beat and the ability to subdivide at slower speeds autonomously. These are all skills that, often, young developing pianists don't yet possess. (Learning how to practise is another topic altogether which I will be addressing in another blog separate from this).
I'm aware this is an issue that divides some teachers. If you're sceptical about the benefits of slow practise, you can read another blog from The Bulletproof Musician here. As always, feel free to disagree - nothing teaches me better than hearing a different opinion! And as always, happy practising!
*"Sipping cocktails on a tropical beach" = Yellowglen Pink at the Moseley Beach Club.