During the late 1880s, the Swiss Army decided to purchase a new folding pocket knife for their soldiers. It was to be suitable for use by the army for two things other knives couldn’t do: opening canned field rations and disassembling the Swiss Army rifle, an operation requiring a screwdriver. Nearly a hundred years later, it was standard issue for U.S. astronauts, who called it a small, cleverly designed, and useful gadget.

The strength of the Swiss Army Knife is that it combines many functions into a small package.

It is at its most useful when you need to be able to do a lot of things in a pinch. The standard knife includes knife blades, screwdrivers, a can opener, a bottler opener, a corkscrew, a punch, a wire-stripper, tweezers, a toothpick, a saw, a fish scaler, a ball-point pen, and so on.

The weakness of the Swiss Army Knife is that it does almost none of these things well.

As a result, it is rarely the first choice for any of its functions, and never for all of them.

Unless you’re far from civilization, you’d never use it to open a bottle of wine or pluck your eyebrows. You’d use purpose-designed tools because they’re more efficient and easier to use.

Your smartphone is a small and ingenious device that does many things, too, but it doesn’t do all of them well, either.

It is fine for browsing, as a phone, and for being in constant communication. It is not the best choice for watching movies, playing games, writing, or calculating. This is why millions of people still buy televisions, game consoles, computers, and calculators and are likely to continue doing so for some time to come.

What about your research?

Most studies try to collect information about too many things at once. One size does not fit all – one size fits almost everyone badly.