Look at any toothpaste ad which shows a giant, beautiful, heaping log of toothpaste which takes up then entire brush head.
That is entirely too much toothpaste and is wasteful. The appropriate amount to use is the size of a large green pea which is often about 1/3 the size as is shown in ads.
The toothpaste companies know this and encourage you to waste their product in order to boost profits.
h/t DefNotTheRealDeal