Pettiskirt full-ness

I want to make a pettiskirt for my little sister,but there is a part that confuses me.When making the skirt,do you sew more layers than usual for more fullness? I really want to make this skirt but this part has me wondering.
 
Help would be GREATLYappreciated.

Here is how I make mine.

for the waist I cut 1.5 times their waist measurement and double the length I want it to be.  Fold in half horizontally, make my elastic casing in the fold.  Now you have raw edges to attach the skirt too.  I add a tier to each raw edge gathering about 2:1 (meaning the second tier is two times as wide as your waist band piece) or for more fullness do 3:1. So you are creating two layers but they aren't connected except at the waist band.  Usually the tiers are the same length but you could do them different lengths for more visual interest at the fluff level.  Now I add a third tier to each tier two at the same ratio you did tier two... Once you have added this it is time to add the fluff this should be done at 3:1.  I only add it to ONE of third tiers not both but you could add it to both.