The best "no drop" system i have encountered is called "corners and sweep".
A rider with a distinctive looking jersey is selected to act as sweep. All that's required is to follow behind the slowest rider.
The ride leader appoints a corner rider to wait at each turn or other place where it's possible to get lost. As soon as they see the sweep rider approaching, they can hop on their bike and ride as fast as they'd like to catch up with the leader and maybe take another corner appointment. For corners, the ride can be an interval workout.
Takes a pretty good sized group to work.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.