Planing is really important. It gets the easy ideas out of the way and then generates the massive creative ones. It also gives you a better idea of what the story setting charters problem and revolution might be.
Circle line circle. Not every plan must follow this format there are many different ways to show planing even just words can do the trick if that is the way that you plan best. Look at this one for example it has more of a mountain look suggesting the problem at the top and the charters setting and revolution on the way down.
They can also help make the reader feel one step ahed of the charter.