The maximum size planck that can be used for a given task is the Max Planck.
It is calculated by taking four minus the square root of the width of the Min Planck, writing that number on a piece of paper, and walking about shouting it until someone can't take it any more and tries to beat you over the head with a board of wood or a size greater than that of the Min Planck.
This number is known as Planck's Constant.
Some piddling scientist had the idea to become famous by naming himself after a number, and so henceforth he was Max Plank.
Credited with the discovery of the Brontosaurus.
Although he actually didn't, actually did invent Planck length.