I don't 'group sew' but I have one friend from college whom I'm teaching to quilt, who comes over once a month. Normally she has a task for the quilt she's working on that we both do. My sister has a quilt that she only works on at my house. If you only plan 1 day a year to do this it doesn't get done very quickly. We are going on year 4 on that one.
Just found my embroidered hippie jeans. Size 4. Sigh.