>If you mess up, redo the part you messed up correctly 5 times in a row.

I think it may be important to note _when_ to redo this. I started off this way, but after working with a guitar teacher (a Berklee graduate), he recommended that I continue on with the song and return to the problematic parts afterwards. If you constantly stop at the problematic parts to replay them and get it right, you'll have no idea what other parts you'll have trouble with further into the song until much later. In addition to that, being able to move on and continue playing the song after making a mistake is an important skill itself. If you build that skill, it's usually only other musicians that will notice -- a regular audience won't.

What's your take on it?

I can be pretty bizarre without even trying, I'll take both ;)

Practice makes perfect is a thing, but that's not exactly rehearsal.

With practice you expect to improve, broaden, or maintain instrumental or musical ability for the long term. There should be no deadlines or need for actual listenability.

OTOH rehearsal is the run-up to a smooth listenable performance with a decidedly short-term objective by comparison. Unless you are rehearsing to absolute perfection, you do not halt for anything, the show must go on and that in itself requires you to practice covering up and compensating for your mistakes or shortcomings as you go along.

With practice you are actually trying to become a better player overall, but rehearsal is more about making the next performance as good as it can be and that's it.

If you're not actually as good as you would like in either regard, having a bit of commitment to simulating what you need most can give some direction itself to add to the mix.

When learning a new piece you should play all the way through once. You should play through it again, stopping at all the problematic areas and making note of them, but continuing. After that there are a lot of ways to go about practicing a piece. I think repetitions on the problematic areas in conjunction with working backwards, especially if you want/need to memorize the piece, is fastest.

Playing through the whole song from the beginning over and over again is not an efficient way to learn a new piece of music.

Not the whole song, just the part you mess up. For instance, in the guitar part for Under the Bridge by RHCP, there's the simple melodic part that only requires learning the chord forms and picking patterns.

That transitions into a more rhythmic chord progression with a few embellishments, which also isn't terribly difficult at first, but then a few verses later that ramps up a good amount and becomes moderately difficult.

If you stumble on that transition / passage, then that is where you would stop and then practice until you do it correctly 5 times.

The next day, once you've rested and let your brain absorb the info, try it again and you'll find it much easier to get right on the first try.

Working backwards is a really neat trick. That's something I wished I figured out a long ago.

I'd say both are important.

Stopping and working slow is the only way you'll find and improve hard things. If you just blunder past them each time, you're only learning to blunder. Able to play the easy things but never improving the hard.

But if all you do is stop at every mistake, all you're learning is how to stop at every mistake. Live music doesn't stop, you need to know how to pick up and keep up, no matter what. (This was my mistake for decades.)

There's a lot more to learning a piece of music, but I think both kinds of passes are necessary. Well, unless you're good enough to fly through that piece prima vista with results that you're happy with. Then you get to hone the expression or interpretation or just cash in, I guess.

As somebody who started teaching himself guitar as a teenager, put it down for 10+ years and started back up, this resonates.

Everything takes twice as long to learn because I first have to unlearn the old habits.

Yes. Put another way: Slow is smooth. Smooth is fast.

And as my music professor once said: "If you sound good while practicing, then you're not practicing."

Guess I’m practicing right

Time is the largest factor though. Some ways are better than others but there is no substitiute for time.

why am I posting here instead of practicing?

Practice make permanent.

This is the one I use, both for myself and the kids. How you practice will become how you play, so it's important to make sure you have good form and technique.

There's another, similar saying used in fighting-related disciplines: train how you fight.

Same idea. You're building muscle memory and technique, so make sure your training/practicing matches how you'd do it in a performance (or fight). It's one less thing to have to think about when you're under stress.