At least a couple times a year, the group just decides it is time to do a project. 2 members in particular do remember to remind us that the reason we are getting together is to improve our bonsai skills. Then randomly ideas will come from the group. I tend to suggest species of plants to get familiar with. Kev tends to propose public events, another tends to propose technique, like grafting or wiring. All with varying degrees of success.
Our first project was "Art Beat in the Heat", a street art fair, and about 6 of us threw together a tent display, we were allowed to do sales too, so there was some selling going on. It was a City of Milwaukee neighborhood art show, where the street was blocked for a weekend. Music, food trucks, mostly arts and crafts, we were the only ones with living plants. This was 2014, I was still in early recovery from a surgery, two of the participants were less than 1 year into bonsai. One had more years in bonsai than me, and more formal training. It was very informal. But fun.
Another project was I went to a nursery, and bought 12 Amelanchier, Serviceberry, all the same cultivar, all the same size - about 5 gallon nursery pots and 5 feet tall. This was autumn of 2014, we still bring the survivors together and compare on occasion. So far they seem much like flowering crab apples, only slower growing and finer twigging. This photo is the last group shot I've got, 2015, I need to find a more recent group shot.
In 2016 I found a group of Cryptomeria japonica 'Lobbii' in 3 and 5 gallon pots, for $5 each from a now out of business nursery. That was another group project. Mortality was high, they are not quite winter hardy in Wisconsin.
We all have Ponderosa pines, that we all bought separately, but regularly we discuss Ponderosa, mugo, Japanese Black Pine, and other pines.
Hinoki has been an informal discussion topic lately.
Every year, for the Milwaukee Bonsai Society Annual Exhibit we all discuss what we are showing, sometimes we do a group display. Sometimes a display will be under one person's name and a stand or accent plant will be borrowed from one of the other members.
So it is haphazard, informal but pretty consistently we do dive into projects, a couple a year.