the 1st test I had with this farm gave me 720 shulker shells per hour. the 2nd test (I replaced the armor stands for snow golems) gave me 150 shulker shells per hour; this is significantly worse rates (however if you build a 2nd platform 8 blocks away in height you can use this method to increase the drop rate by 150 shulker shells per layer you add) and my 3rd test (resulted in returning back to the original design) and I proceeded to get 789 shulker shells per hour so this farm being promoted at 710 drops per hour is a little low (but IMO it's better to under promise and over deliver rathee than over promise and under delivery)