I did something similar when training for a marathon during a busy time in my life. With work and life I didn\'t have the mental energy to put in formal workouts. I did enjoy the higher mileage though as my downtime. Instead of workouts I would just add in long pick ups when I felt like it, surging to the end of the street for example, repeating that about 10 times in a 12 mile run.
I didn\'t go into the marathon with any high expectations and ran a 2 minute PR. I\'ve since added formal workouts and set a better PR, but for that training cycle I think the higher mileage made up for the lack of intensity. Do I think it would work for every training cycle? Probably not, but it worked then.
I can\'t say how it would work for shorter distances though.