Maybe the issue is cushion size ? depth ?diameter ? i've seen some of the large bags used very effectivly for a seated kneeling shot as such.
In Hungary 2010 they measured depth of cushions,maybe they should be a set diameter and depth across the board ? so it is the same for everyone.
there is a rule that states,the bag should not measure more than 100mm when compressed between two boards.
Not sure what advantage a thick bag give's,but it seem's a rule that get's overlooked.
About as much use at field target , as a life guard at the Olympic swimming pool.