You should only learn from people who draw in a way that is exactly how you would like to draw. You should only copy or study images that are exactly what you wish that you could draw.

If you practice things that you don't 100% love then those things will still seep into your mind and you will end up unconsciously incorporating elements of it into your other drawings. If you love the art of your teachers then that can be a great thing when you start to see your art during into a mini version of your teacher's art. If you aren't careful with what you allow influence you and you "learn" from things that you don't 100% love then it can be like poison that seeps into your art.

Never watch youtube art tutorials