Distance Override is a great feature for running and also rowing. It gives you more control over the repetition distance — meaning the length of your stride. For example, you might have a five-foot stride length while running but a three-foot stride length while walking.
Your Atlas watch will estimate the repetition distance based on your height, but you can always adjust it using Distance Override.
This is important because it impacts the number of reps you'll need to complete in order to achieve your Distance Target.