I am all about slow practice, something my teachers pounded into my head until I got it. When you are a kid, you want to play everything fast, but you have to SLOW IT DOWN.

Like to 40 BPM.

It took my a long time to realize this, but you have to spend some time playing songs perfectly at a really slow tempo because you are forming muscle memory and also building muscles.

If you gloss over things--and gloss over mistakes--at higher speeds you will never learn the muscle memory to play them correctly. Ever. So you HAVE to practice slow, or have some slow practice in your regimen. It took me years to figure this out and discipline myself to practice slowly.