There is a careful and there is a wasteful way of spreading butter on bread. The Cumberland way I have always thought very wasteful.
It is vigorously scraped and worked into the cut side of the loaf, and then the buttered slice is cut off. In this way, I have seen — and tasted — the bread impregnated with butter; there was as much of the one as the other, and yet it did not show much on the surface, as it was well worked into the holes.
Now, however nourishing butter may be, it is an expensive food, and no one wishes to have more of it than pleasantly tastes the bread. The correct way to spread it so as to get the full flavour with greatest economy is to cut it off very thinly with a sharp knife and lay it on the bread with as little pressure as is necessary to make it adhere and have an even surface.
This is even more important when the butter is soft than when it is hard as we all know how quickly it disappears when rubbed on a loaf. Don’t rub, and your butter will go farther. The tongue gets the flavour of it too, much more cleanly and fully when it merely lies on the surface of the bread.