I think 2giftgirls put it well with her example of guitar lessons. I have posted similar stories about piano and DD7. She just had a recital on 2 pieces she was not found of, a slow Tchaikovshy was one. And her teacher has a very high bar of how she wants pieces played. I worked with DD and pushed her to do it as the teacher wanted, saying that if she didn't do it now, the teacher would delay the recital until it was right. And she got it done and she played amazingly and after she said she felt proud that she had done the work and did so well.
Coasting allows you to do OK. Even if you get A+, a lot of time you don't really learn it. You learn it to regurgitate it.
It is how you use your mind. Einstein worked in a patent office. Instead of just sitting there approving patents, (talk about outliers and opportunities) he used his position to look at all these time synchronizers and apply it to space and time, to create a new physical way of thinking.
So what does coasting give you? A "C", for cheating yourself out of opportunity.
