I make my bow limbs taper from 3/4" at the handle/fades down to 1/2" thick at the nocks to start with. I make sure the belly is flat before I even begin tiller, that way I know both sides of each limb are even taper before I even begin tiller.
I work my floor tiller before using my tiller stick. Wherever I see a stiff spot I mark with a pencil straight lines from one edge of the limb to the other and then scrape the pencil lines away, this guarantees you never remove more wood as long as you make sure you remove your pencil lines each time. Works for me. Draw the pencil lines from one edge of the limb to the other where the stiff spots are each time you test the bend either on the floor or tiller stick. As long as you remove all the pencil lines each time you will always remove equal amounts of wood assuming your sides were equal before any tiller began as I explained earlier.