Hmm. They have worked well for me for over 12 yrs using one patch. Granted herefishy, I fish barbless and don't usually go larger than #16 flies but I've not had any trouble.
The most used parts of my grey, foam patch have lots of holes so I cut some (5-6) .2" wide x approx. 3" long x .09" thk. tough foam strips from the .09" thk. sheets you get from your fly shop and super-glued them on top of the patch where the hooks stck and I'm good to go for another decade or more.
Now wait, just my luck the safety pin in back'll bust....)
Jeremy.