I've been leading rides on 2 wheels for nearly 3 decades. My personal take is this.... keep it a tight group with lower numbers and preferably people that you know and trust. That is the easiest. I prefer no more than 6 behind me, but have done rides with many more. Myself and one other guy still put on a ride in September every year, as a benefit to some local needing person or family. We have dealt with up to 100 bikes, and at that point it's not really as much fun as it is work. But it's for a good cause, so we continue to do it.
But with all the rules, and the people that have no idea what it's like to ride in a group.... that leaves me and my wife to be mainly Lone Wolf riders, both in the Slingshot or on the Harleys.