That decision, like many others we make, came down to a single fundamental principle of preparedness:
"Two is one, and one is none."It's a truism closely related to Murphy's Law, "shit happens" and "best-laid plans" -- having a tool or a plan is essential, but having a backup can save your life.
My wife and I view magazines as consumable items, arguably the weakest mechanical link in the armed-defense chain. Being prepared with two loaded mags is a no-brainer, really, and for us that means three, assuring us of two -- which is, in principle, one.
Beyond this case-in-point are myriad other examples of our pattern of three-fers, notably:
Starting a fire (matches, lighter, firesteel);It's less versatility than contingency. Nessmuk and Kephart advocated their trios, a concept evolving from the need to accomplish multiple tasks, not from a wish for redundancy. Their approach is instructive, however, if not quite parallel, and it can be useful when extended to the rest of a preparedness scheme.
Purifying water (boiling, chemicals, filtration);
Communication (mobile phone, GMRS, CB); and
Evacuation (three escape routes, three shelters).
It's a mindset thing.
And so, whenever possible, we prefer to have three. Actually, specific to magazines, we consider it wise to have ten (at least) for each firearm -- but that's another story for another day.