Base mileage, trying to find the sweetspot

As I posted last month, I increased my weekly mileage from 40-50 miles per week ("mpw") to 50-60 mpw. On the high end, that's a 20 mpw difference and I can definitely feel the impact after 4 weeks of averaging 60 mpw.  Now I'm asking myself "why" and what's the advantage of maintaining a 60 mpw base as that's a heavy base for a 40-something :).  To maintain the 60 mpw, I have to throw in 1-2 doubles per week and it can take a toll in terms of limiting recovery time which can be an issue as you get older and, of course, there's always some differences based on the individuals make-up, including genetics.

As such, I'm taking a very close look at the impacts and value of the increased mileage.  It makes sense when I'm training for a half or full marathon but since I'm not training for a longer distance race, is it worth the increased weekly mileage just to increase my base mileage?  It's a tough question and something I'm looking at for myself.  I've also run 57 consecutive days and I'll also re-visit the value of a rest day although I'm less concerned about a rest day and more focused on the impact of the increased mileage.

My body has always responded and recovered from speed workouts faster than too many long runs and that may be an individual thing.  The deep question will be the "why" for me . . . why run 60 mpw vs. 40 mpw and it's a deeper analysis than just saying "because I can."  I've proven I can but I need to go deeper and correlate the mpw to happiness and health.  I'm in the process of doing that right now :).

Harry