Any comments on this data: https://www.instagram.com/p/Cf3wMmgO_qF/?utm_source=ig_web_copy_link ?
Seems to suggest that there's an almost immediate drop off in foam integrity.
Personally, I will only do an A race in a brand new pair of super shoes. I do less important races up to about 250 miles, but usually by that point I have another fresh pair coming down the pipe from my last A race, and then the shoe becomes just for workouts.