on1y once/ container / container

How many times do you push the head of a shampoo container when you do shampoo?
Most of people push the head of a shampoo container couple of times because people think that pushing once is not enough to do shampoo and make bubble.
It makes environment pollution due to that waste and too much usage is harmful on users' hair skin.
I suggest the way to think about environment according to the slogan, Only once!, and the head of the container which looks like number one. It would help reduce usage of a shampoo. People will emotionally and aesthetically satisfy by Only once.
Once is enough to use if your hair is long or short.