You're probably learning (reinforcing) more than one skill at a time, in different proportions. Sometimes you unavoidably reinforce a bad thing but it's still worthwhile in order to learn a good thing at the same time. It's very good to be aware of all that you are learning - so I suggest formulating your question in the plural: "what skills am I training, at what tradeoffs?"

For example:

• You're going to make some mistakes as you learn a new piece of music; as you practice more, you stop making mistakes. There are better and worse tradeoffs in terms of initial playing speed and mistakes made.
• While students learn to take notes (irrelevant) and parrot the teacher's answers (mostly harmful), they also learn actual math, and this can be a great tradeoff.