For the first thirty years of your life,
you make your habits.
For the last thirty years of your life,
your habits make you.
– Old Hindu Proverb
We tell kids that their homework is important, even when we know the task itself is not. Most of the time, the real task is learning how to learn. Most of the time, the biggest benefit of otherwise meaningless work is building the right habits.
This doesn’t stop in grade school. It’s important to do it right, even if no one will ever see it. If you get in the habit of being sloppy, someday you’ll be sloppy when it matters, ironically because you won’t be sharp enough to tell ahead of time when it’s going to matter.