For long hair ranging from about 2 teaspoon of shampoo, which is mixed with water seems even more productive.
An advantage with long hair: The hair after washing have such a good quality that the hair-washing must be done with long hair only every three days, rather than as usual with a drugstore shampoo every two days.
Another advantage of the Redken All Soft Shampoo is the same but its drawback! What does this do? So: The hair is very soft, very soft after washing in combination with the appropriate conditioner. The advantage are indeed beautiful soft hair, but the disadvantage, because of the soft hair, it is necessary to use more mousse and more hairspray. That is why I reach but then only intermittently on the Redken All Soft Shampoo back and use continue alternating a good drugstore shampoo.
I would recommend the Redken All Soft Shampoo anyway because it is reasonably priced available at Amazon, in the barber shop it costs a few euros more.