I find that numbers work well ONLY if everyone wants to be in a group.
I did a multi-day trip down the Colorado and the two trip-leaders told us at the put-in, "Everyone is on their own so I hope you all are prepared."
Often we'd be on the river or working our way among the bypasses and find the leaders gone, exploring a new path through the reeds.
Another time, the group was in a side-lake, relaxing so I yelled that i was taking a pee-break. When I was back i nmy boat, everyone was gone and I had to find their trail on a river-slake system that was overgrown with cattails on a river I had never paddled.
On the plus side, hauling an entire tent and cooking and eating gear yourslf loads a boat. So if you spread the load: I carry the tent, she the poles, he the fly and hammer, she the sun-shade.... I carry the stove, she the cookware, the food is passed around for all....
And if someone vanishes, it is easier to find them if you have a group searching.
of course, this only works if the group is close and willing to share and work together.
most of the time, I find the group will share food but nothing else, unless they are married.
Touring Kayak Paddles
PFD's (Life Jackets)