I think syndicates work OK at two levels:
1) a very small one comprising of a few good friends
That is definitely the best way, although each member has a larger share of a bill than would be the case in a big group, so they need to be solvent and able to put their hands in their pockets.
However, you'd be amazed at the way good friends can fall out over little matters. The best group of all is a group of one.
I've come round to the view that, if you are in a group, it should be run on company lines with a strong contractual obligation on members, rather than relying on goodwill.
When I acted as group treasurer I found the pressure from members intolerable. They wanted the aircraft properly maintained and in a good state of repair, but I had to chase them constantly for money.
As this was an unpaid, but ultimately, thankless role, I felt badly-used by the other members and eventually gave it up and left the group with a lot of bad feeling.
I hope the XX621's group can get itself back on track, but I sense that it may have got to a point when it should start divorce proceedings.