Not sure because of the different types of quilts I have made but I am thinking about 6 or 7. This includes cutting the long ways on the yardage to then segment it out with a small appropriate ruler into blocks. Squaring up the quilt and then making the binding with too. Then any squaring up as you go rulers. Or a specialty ruler for those types of blocks.
It really depends, right? Boggles the mind really to try and figure it out because of the different quilts we make.
Oh, and sometimes I use my rulers to mark quilting lines.