100 miles seemed to be the limit of dual 6mm EVA sheets.  Only 1 sheet fully disintegrated.

The compression after 100 miles was less than a flip flop.

A way was revealed to swap the EVA without completely undoing the string.  Getting the lengths right continues to be a problem, since the lengths change as the foam compresses. Toe taping & careful placement of the cable farsteners has allowed the string to be tied at any tightness without chafing.  It might someday be practical to use knots.

Definitely time to invest in a 1/4" hole punch.  The only ones big enough are the hammer & chisel type.  Drilling holes with the drill bit & exacto knife was terribly inaccurate, whether or not it weakened the material.

With OSH joining the retail closures, the Lehigh NML48 string which was so easy on lion paws is a lot more expensive.