i remember reading somewhere that rubber degrades over time, so if you're applying the trampoline mod you'll need to replace your o-rings once a year or so
Trampoline mod uses silicone balls inside the switches, not orings. And they last a long, long, long time. Also, most rubbers used for orings last a lot longer than a year... They slowly lose oils and dry out and toughen / become more brittle, but there are some VERY old rubber dome boards still functional. Also, Topre switches use rubber domes and they last, well.... very long.