No, length is what your looking at. The bug should not be any longer than the distance (width) between the dragons eyes on a dragon under 1 year or 16 inches. Sub adult and adult dragons that have reached 16 inches in length no longer have the slight bend in their digestive tract where blockages can occur from too large of feeders/to chitonous (harder shelled like supers) so the size of the feeder is not as critical after reaching this size. There are some exceptions, for example, my 8 month old male Assassin is almost 22 inches long and eats adult sized, 2 inch dubias. He is more than large enough to be able to digest them. Most 8 month old dragons are still under that 16 inch range, so 1 year is about average time frame.
Hope this helps. Any more questions, please ask.