My rule of thumb for this is:
Carry what I think I will need "out" and keep a redundent item one "level" up in my kit - aka, on person, in backpack, in truck, in house

BUT I'm NOT afraid to "raid" a different kit for use, BUT if I find that I'm raiding a kit more than "rarely", a "Use" version is bought, and "stored" version is stored

AKA - I have a knife on me, and there is a backup in my bag. Now I have a small flashlight on me, but if I find myself going for the bigger flashlight more than every once in a while, I'll buy a bigger carry flashlight, and also keep one in the kit.

Just remember: 2 is 1, one is none