I think you have stated the two possibilities:
1. keep the group together
2. paddle solo even though a group launches from the same place and leaves at about the same time
The paddles I've been on have sometimes started out as 1, but have quickly become 2, because the faster paddlers did not slow down. By simple logic, keeping the group together is the faster paddlers' responsibility. Slower paddlers can't paddle faster. Faster paddlers can paddle slower.
There is generally an agreement about destination and route, but rarely about keeping the group together, so paddlers get strung out all over the route, WAY farther apart than would make rescue easy or even possible. This is not only a hazard to kayakers, it is also a lack of courtesy to larger craft in the area.
What is your suggestion?
The Connyak BBS