We are trying to resurrect our high power rifle team at our gun club, and I was speaking with one of the former team members about gear and such. He brought up an interesting idea, that plays well with our ideas here.
When he started, he took an empty tool box and put a few items in it. Every time he needed an item that wasn't in the box, he'd get it, add it to the box, and never remove it. If he needed the same item elsewhere, if he couldn't use it and immediately replace it in the box, he wouldn't take it out, he'd get another of the same item for the other use.
I thought this translated well here. Start with a basic EDC, FAK or WTF ;-) and add as you see fit. As many have brought up before, kits vary based on individuals, locations and needs. The key though, is never remove an item that you really needed, because the odds are good that you'll need it again.
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It's not that life is so short, it's that you're dead for so long.