When my clients are trying to decide how many extras of things they will need, I ask them to consider a few questions:
–How expensive is the thing? Would the cost to replace it be insignificant or a major outlay?
–How easy is it to obtain the thing? Is it available in stores close by? Would friends have one to lend you? Or do you have to travel a great distance to get one?
–How immediately would you require the thing? Toilet paper is a good example. 🙂
–Does having extras of the thing add to a bad household clutter situation, which will make it more likely that you won’t be able to find the thing anyway and therefore buy more of it, which will add to the clutter, etc.?
–Do you have enough room to store extras of the thing? (Seems like that’s a big part of your decision making process). Limiting it to a certain volume is good.
–Have you historically gone through them frequently (using up, losing outside the home, or breaking) or needed multiples at once? Power strips/extensions are an example of needing several at once.