It could hurt, but it might help...although "sub 60" isn't necessarily sprinting. For some people it is, but for most people who would even think about "100 mile sprint weeks" would have a sprint speed closer to 50s/lap.
Many great runners have done short efforts on the track or roads repeated MANY times...think Zatopeks interval workouts or some other runners who did 20,30,40+ wind sprints/strides after easy runs...there are many ways to get endurance, and hard efforts with short recoveries often works better then easy/moderate effort over a long time.
But 100 miles is a bit too much. Actually way too much.