I agree it's not worth the effort when there is insufficient interest. Where I am, this type of group meeting seems to be done by LQS only. They typically require sign-up and a fee paid up-front for the get-together sessions.
One thing I found with these types of get-togethers, even when done in the LQS, is that the chairs and tables are really not appropriate for sewing machine work. My back cannot take metal folding chairs with standard tables.
Some of the intimate groups that last a long time seem to originate as offshoots of a quilting guild. Typically the members meet in each other's homes, taking turns every month. It helps if people live near each other and if the weather is halfway decent.