Imagine that half the cars in the US get 10 miles per gallon. And half get 40 miles per gallon. Further stipulate that all cars are driven the same number of miles per year.

Now, you get one wish. You can give every low-mileage car a new set of spark plugs that will increase fuel efficiency by 5 mpg, up to 15. Or you can replace every 40 mpg car with a car that gets 75 mpg, an increase of 35 miles for every gallon driven.

Which is better?

It turns out that the 5 mpg increase is far better for overall mileage than the 35 mpg increase, even though it’s smaller both as a percentage and absolutely. That’s because the 10 mpg hogs use up so much gas. They’re the low-hanging fruit, not just easy to fix, but worth fixing.

As marketers, we’re tempted to tweak the already tweaked, to turn the 100 to 101, to optimize for the peak performances. That long tail is very long, though, and if there’s a way you can raise the floor (instead of just focusing on the ceiling) you may be surprised to discover that it can have a huge impact.

Simple example: It’s way more profitable to encourage each of your existing customers to spend $3 than it is to get a stranger to spend $300. It’s also more effective to get the 80% of your customer service people that are average to be a little better than it is to get the amazing ones to be better still.