I've been listening to the Huberman Lab podcast[0] recently, and in one of the earlier episodes he talks a lot about how to create the environment for neuroplasticity in the adult brain. I've only listened to most episodes once so I hope I'm not misrepresenting him, and this is simplified, but a critical component of causing the release of the chemical bath which allows for robust neuroplasticity is making errors, an experience which should feel a bit uncomfortable. "Errors are the basis of neuroplasticity." Without that focused set of attempts and discomfort of trying to do something and failing, the brain isn't getting the high quality signal that it needs to do some rewiring because the current networks simply aren't making the cut.

This is at odds with a quote from OP's second point:

> If you keep making mistakes when practicing then you are just going to get good at making them, so it’s best to avoid them in the first place.

That aside, the article seems like great advice. With Huberman's account of encouraging adult neuroplasticity in mind, my thinking would be to amend this method towards going just fast enough to be able to do the chunk of music but not so slow that the attempts are free of errors. And probably the errors should be of one type at a time? Instead of erring in dynamics and fingering and articulation all at once, try to get everything right except for one aspect. For that, attempt to surpass your abilities and err.

[0] https://www.youtube.com/c/AndrewHubermanLab/featured

Edit: Said another way, “perfect practice makes perfect,” where you aim to play perfectly but consistently just barely fall short. The correct networks are strengthened while those tiny errors get tweaked via neuroplasticity the nights after and consistent improvement results.