What is "good"? 

The answer to this question can actually be a series of questions: What are we specifically talking about? And in which context? And to whom?

In other words, to answer this question you have to juggle a number of variables in your mind, and even then you may not find an answer, and stifle yourself in the process.

Imagine not going to the gym because you can't quite figure out the "perfect" routine for yourself. You can get hung up on trying to make something perfect, to the extent where you end up not really doing it.

And so I'll spare you the hassle, and answer that question for you:

It does not matter.

Whatever it is you're trying to achieve, or be "good" at, realize that you can only get there through constant repetition. This means that, in a way, "quality" is simply a by-product of "quantity". 

Once you internalize this, you realize how having a "perfectionist" mindset can actually stand in the way of your progress. 

So instead of chasing what's "perfect", focus on just doing it, and in time, your muscle memory will take over.