>Like you'll see much larger gains adding 10+ miles per week to your training volume.
me personally? I won't as I row 35/40km a week.
The overwhelming majority of runners are running less than 30 miles per week. Competitive amateurs might be doing 40-60. Most would see better than 4% improvements adding 10+ miles to their training volume.
I used to run competitively in my teens. Now nearly 40 and getting back into it. Recently upped distance to 50 miles a week (mostly slow) from 20 and I’m suddenly doing sub 17min 5ks. Couldn’t get below 19 mins before upping mileage.
if I add ten miles to my running it is purely mechanical conditioning, I'll see zero improvement in my physical strength, respiration, mental resilience...so I would expect very little added benefit...at least less than I'd probably see with more forgiving shoes.
It's the most reliable way of improving performance to the point that increasing Zone 2 volume alone can drive huge performance improvements at sub-elite paces, much more than the 4% we're seeing from these shoes.
Adding ten miles will absolutely increase respiration and mental resilience, because every minute added taxes those faculties, and time on feet is a huge part of conditioning your lower legs to handle the volumes of really long distances. You can be cardiovascularly advanced but have trouble with longer distances without specific training, but training for marathons often improves your performance at every shorter aerobic distance.
If you want to improve physical strength, do strength training. Shoes won't do it for you.