What is it about?
This is a concept from a book Great by Choice ~ Jim Collins, which says that for a long distance, a slower but regular pace is better than a sprint. In other words — it's about moving at a steady pace regardless of an extenral and internal factors. This includes how you feel, how much work do you have and any unpredictable circumstances.
How do I use this 20 Mile March?
A concept of a steady pace helps me develop my Process so it can become Antifragile. For example I could record 3-4 videos a week and publish on overment. I record one, but because of that I am able to do it regularly (as long as it is a priority for me).