I love this thread. My guild did an opportunity quilt made of member blocks. They were paper pieced. This really helps with the precision issue. With instructions not to trim them.
QOV has done block drives and the block is always something that is made much bigger and will get trimmed later.
I hate sewing donated blocks together. Sometimes you just have to put a frame around each block and trim to a consistent size.
I sew with friends all the time but we each have our own projects to work on. I love sewing what everyone is making and often get ideas for something I would like to sew.