Clubs vary. I'm a member of the Atlanta Bonsai Society. I'm also a defacto member of Bay Island Bonsai. They're very different!
BIB has a Sensei, and all the members are required to take a certain number of workshops each year with the Sensei. There's an annual show put on by the club, and the trees have to be approved in advance by the Sensei. The trees are all at a level equal to or superior to those shown at the National show. Much smaller, obviously. But extremely high
quality. The awards are selected by a vote of the members. The Sensei chooses 5 or 6 trees in each category, then the membership votes for their choice to receive the award.
The Atlanta club meets monthly, and brings in 3 or 4 guest artists for workshops each year. The annual show usually has a headliner artist to help set up the show and judge, as well as conduct workshops and a demo. There are categories of expert, hobbiest, and novice for judging. The idea is to promote participation. Since all are encouraged to show, the quality of the trees on display can vary wildly. Unfortunately, while most novices are quite happy to enter in the "novice" category, few enter the "hobbiest" category! They all think they're experts!
From what I understand from talking with friends, in California and other parts of the West Coast, there are a number Sensei type clubs. They are rare in other parts of the country.
The benefit of the Sensei types clubs is everyone works within the guidelines established by the Sensei. Trees tend to progress because the Sensei helps to set the long range view in the beginning, and refines it as the tree progresses.
The serial guest artists type clubs fair less well because once the guest artist leaves town, the club member is left on his own. The next guest artist may see a different image, and restyles the tree in a different manner. This happens a lot.
So what happens is a small group of members form a "study group" and bring in the same guest artist a couple times a year, outside of the Club. I know of two such study groups in Atlanta. These members trees progress, but the rest of the larger Club's do not. And the study group members are reluctant to support the visiting guest artists because they want to stay focused on their sensei's program.
I don't have a solution to this. I'm just making an observation.