[RigelKentaurus]

I play electric guitar at a decent speed but want to get very fast, say ~600 notes per minute (npm). I had two guitar teachers who gave me conflicting advice:

1) Practice doesn't make perfect, only "perfect practice makes perfect". Use a metronome, start with a speed I'm 100% comfortable with, and slowly build up my speed at 5 npm intervals. When I start making even minor mistakes, stop, go back 10 rpm, and hold my practice there for 5-10 minutes. Keep to this technique and I will get faster over time.

2. Don’t aim for perfection. Get comfortable with the concept of fast playing in my mind, and my fingers will follow. Warm up a little, but after that, jump to playing at my target speed, even if it sounds sloppy. Repeat this enough number of times and I will get faster over months and years.

I’ve tried both techniques over the last 3 years and have gotten considerably faster. But I'm not sure which of these techniques has worked more than the other.

My own take is that it takes time, and staying on the edge of what I’m capable of doing is important. No rules beyond that, really.

Question for this audience, especially for musicians and guitarists: how do you structure your practice to become great?

[PandaRider]

Not a guitarist (take my comments with a pinch of salt).

Your teachers are both right: Either advices (1) or (2) works as long as the practice is hard.

That said, while (2) may sound easier because the approach pursues "comfort in the mind" over perfection... this is still hard because because by definition: you still need to get from uncomfortable to comfortable!

A similar example in bodybuilding: muscle confusion [1]. To build better squats, one requires both compound(2) and isolation (1) exercises

[1]: https://www.nytimes.com/2020/01/08/well/move/muscle-confusio...

(Huge Caveat: this only applies to physical deliberate practice!)