The psychology of the supermarket shop sometimes seeps into the mind of a client. We’re used to going in to pick up a toilet roll and waddling to the car with enough BOGOF rolls to insulate the attic. But getting more for our marketing pound doesn’t necessarily mean volume. Less often costs more. Because it’s much harder to come up with the three words that epitomize your brand (Coke Is It or Nike’s Just Do It), than it is to write a guide to...