WHY NOT JUST CLEAN UP THE LEAVES AT THE END?

A boy turns to his father and asks, "What is the point of raking the leaves when there are more still on the trees? Why don't you wait until all of them fall so you only have to rake once?" The father says, "There are many things that we have to do over and over in life, son. In fact, if we do something for a worthwhile result, why would we only want to do it once?"