Keep it simple; do one thing, and do it the best you can.

That is the formula of In-N-Out Burger, whose menu consists of only burgers, fries, and shakes. NPR's All Things Considered has the story (7/14), from which I learned about In-N-Out Burger's peculiar history: everything from their secret menu to how most patrons fail to notice the bible verses scribbled on the bottom of their cups.

The big question in my mind is if this "keep it simple" formula is so vital to success, why are similar strategies so evasive in the restaurant industry as a whole? Having a really good burger is not sufficient for success because a burger can be easily reverse-engineered. Success lies in doing multiple things well: The more things you do well, the harder your success will be to replicate. There must be something other than really good burgers -- I don't know if it is the price, convenience, speed of service, or aura of their weird biblical history -- that is keeping customers coming back, but it must be something. At least that's my guess.