Recommened quantity of sound dampening pad?

I have a 2018 Prius Two.

I would like to sound deaden the cabin. Primarily focusing on the doors and trunk space. I am leaning towards getting the KilMat 80mil or 100 mil pads but do not know how many to order.
Can anyone give me advice on the amount I should buy to cover the front and rear doors as well as the trunk space?.
I plan to put some behind the factory woofers too in the hopes that it will allow me to not need to replace them. I currently have to crank the volume to ~30+/- to hear podcasts.