Dumb question??? NO!
But, there used to be backing fabric specifically marked and sold to be quilted from the back not the top of the quilt.
Then, again, if one is interested in an allover pattern, one can just follow the design in the print on the back to get the same effect.
Asfar as the 'bunch' in the middle of a pinwheel, have you ever learned to split the seams? This DOES NOT involve cutting them in any way!! It'smerely done by easing open a stitch or 2 within the seam allowance and pressing the seams in opposite directions. You can see this very easily on the back of a 4-patch block......lightly twist the seams so that the tiny intersection creates the same little 4-patch that the front of the block has. Just try it and see.
The pinwheel and other similar shapes can be done the same way; and they also make the same shape in that tiny seam allowance joint as the front of the block.
Jan in va