Refactoring legacy code can be daunting. While trial by fire is a great way to learn most kinds of programming, it doesn’t leave a lot of room for getting better at it (at least not quickly).
When trying to hit a deadline it is often difficult to take a step back, try different techniques, and learn a few keyboard strokes to automate some of the more mundane tasks. Coding katas are one way we can hone our craft outside the pressure of deadlines and our day jobs. It’s even better if your day job encourages spending a little time now and then to improve.