It takes a long time to wear out a Birkenstock, a favorite sandal of Boomers (with or without socks). Here's a comparison of a new pair to an old pair worn daily
BIRKENSTOCK KAY SL DOG BLUE CAT RED CLOGS SABOT SLIPPERS WOMEN PROFESSIONAL | eBay
Birkenstock Arizona Essentials EVA | Waterproof Birkenstocks – Footwear etc.