I consider the swaps that are done on Quilting Board as quilting with a friend, although virtual. I've done several of them. I've been very pleased with the Boom swap blocks-- they were all sewn well and the same size. I did swaps where all in the group made the same pattern for the blocks, then we swapped. I understand that everyone's taste in fabric is not going to all be the same and that kind of swap would produce more of a scrappy look for the quilt, and I was fine with that.
I did one round robin where a top was missing in the mail for a long time, and that was not fun, but it wasn't because of the girls in the group. I thought it was very fun to sew together with quilters here on the Board. Each brings their own flavor to the project that when melded together create a unique and special shared endeavor.
I did a round robin with friends in my local quilting group, and that was a ton of fun and produced one of my all time favorite quilts.
I did an individual block swap with a friend, where we agreed on the pattern together, then agreed to use plaids. The blocks were great, and the friendship was richer because of the shared project.
The friend I sew with most often is my sister. We chose fabric together and have used modern, traditional, or novelty prints. We mostly choose fabric that is on sale actually, and agree about the price. lol When we get together, she cuts and irons. I sew. Then we lay out blocks together in a pleasing manner, she hands them to me, I sew, and she irons. It all works out great. We chat, have tea and a lunch, and get a lot done in one day every time we do it.
I think the key to being happy sewing together is to be kind. Accept construction flaws. Accept colors, patterns, or fabric you don't particularly like. Accept that what you make together isn't what you make alone-- and be generous in your mind, in order to enjoy the process and like the result.