An analy­sis of super­mar­ket check­out times has shown that express lanes (for peo­ple with fewer than 5 items, say) are not always the most effi­cient check­out route for time-sensitive shop­pers.

Dan Meyer, a high school maths teacher, has done the hard work (pro­vid­ing his data and analy­sis) and came to the fol­low­ing conclusion:

[Express lanes] attract more peo­ple hold­ing fewer total items, but as the data shows […], when you add one per­son to the line, you’re adding 48 extra sec­onds to the line length (that’s “ten­der time” added to “other time”) with­out even con­sid­er­ing the items in her cart. Mean­while, an extra item only costs you an extra 2.8 sec­onds. There­fore, you’d rather add 17 more items to the line than one extra person!

via Kot­tke