Already in the 60s of the last century, the manufacturer Alka-Seltzer came up with an elementary, but extremely effective thing. If earlier in the commercial roller was thrown one tablet of the drug, now they started throwing two. The result was not long in coming – as expected, sales doubled.
Later such a move was borrowed by other brands. All known examples: chewing gum with two pads, toothpaste with copious application to the toothbrush, shampoos with at least two applications, etc.
Thus, the consumer was shown an example of how to “correctly” use the product. And they increased their sales by the usual trick.72