In my neck of the woods, nearly every "road" bike club looks to be using the regular paved streets.

The "paths" are where some commuters go, where slower cyclists go, and where the multi-use others (pedestrians, folks walking dogs, skateboarders, etc) go.

Seems the proper way to use the paths, around here. Faster folks are where the cars are; slower folks tend toward the MUPs when MUPs are available. Works well.

In some of the larger parks, there are some very wide, purpose-built MUPs designed for a greater number of cyclists, and many of those appear to easily deal with somewhat faster-moving cyclists.

If there were vastly more MUPs around, I suppose it'd be far more usual to see "group" cyclists and faster-moving cyclists using such paths. But, there aren't.