There is something to be said for this, but it really is a balancing act.
I was a decent college runner, and a good one for a low mileage runner (I didn't start running in college, so my mileage build was slow and I had a penchant for injuries).
After college, I had lots of gaps in training, and basically ran 30-50 miles per week.
As I approached 40, I decided to see if I could still break 16:00 for the 5k and was able to do it. I still didn't run a lot of volume. Maybe 50 miles per week at most. The key was getting back under 150 pounds for the first time in a long time.
After that, I decide that running my first marathon might be a good way to keep myself interested in the sport. So my volume really increased. For the fist time since college, I got up into the 60s, and for only the second stretch of running ever, I got into the 70s (I only went over 70 miles twice in college, during one stretch my junior year - I promptly got injured).
My 5k times dropped even more, getting into the 15:30s on the road and down to the low 15:20s on the track.
Increase my mileage for my second marathon and got into the 80s regularly (first time ever exceeding 80 miles), and peaked out at 100 miles. Had a great race outcome, and ended up with surgery 6 months later for the plantar fasciitis that reared its head during that marathon training cycle.
Got into the low 90s for my third marathon, no major issues.
Started training for my 4th marathon, and ended up with plantar fasciitis (other foot) posterior tibial tendinitis, and, eventually a stress reaction. Bagged Boston, took some time off and recalibrated for Chicago 6 months later. Had to reduce volume and add in cross training. Set a PR. Ended up with another surgery for plantar fasciitis.
Bottom line: more volume improves race outcomes, as long as it doesn't break you, and in your 40s, breaking is a lot easier than it used to be.