A small amount of fullness can be quilted down, but if there is excess fullness in your quilt there may be small puckers and folds. I will do my utmost best to avoid this. You can check to see if there might be problems on your quilt by measuring both sides and both ends, then measure in the middle. The three measurements for width should closely match, the same for the length measurements. The quilt should lay flat.  Let me also say that I have quilted many 'imperfect' quilt tops and they have come out beautiful!