Whats a good lesson you learned on the job?

For me:

Sometimes it doesn’t matter how hard you work, your going to get laid off either way.
Just showing up can sometimes make the difference.
Your not paid to be a software developer. Your being paid to be a problem solver.

It usually doesn’t need to be perfect, good enough is often good enough and can be a lot faster where trying for perfection might not get finished in time.
Perfect is the enemy of good - Wikipedia