This is a bit too general. Depends on goals. If you a long distance marathon runner you can’t possibly achieve your peak at 35 miles a week. Some of it is math. Your long run for example is supposed to be 20–30pct of your weekly mileage. Let’s say your weekend long run is half a marathon which is not unreasonable. That means your weekly mileage should be 50-60 miles and it makes sense - no point in running lots of miles on a single run if the rest of the mileage is not there. So while 100 miles a week may not linearly improve your performance compared to 60, there is certainly some meaningful minimum volume that does matter