Are you concerned with feeding supers which are too big. If your dragon is a year old I wouldn't worry about it. In terms of length they can likely be a bit longer then the space between their eyes.
My dragons are still 5 months old, and I use supers as substitute staple when my cricks run out like now because of the cold weather my cricks are growing slow and too small to feed them. :-(
My dragon is a 16 inch long adult. I'm not sure what the space is between her eyes, but she eats full sized adult superworms with no problem. The worms are definitely longer than the space between her eyes but she handles them with no problems.