I checked my various kits recently...

Meds expired in the first aid kits
The polyurethane lining in a backpack is getting sticking. In other words, it's breaking down.
Does duct tape deteriorate? Wondering if I need to replace a 10 year old roll...

There seems to be this inevitable replacement cost. We buy some equipment that doesn't get used unless there is an emergency. Then ten years later it's no good anymore.