The Round Robin that we did here on the Board a couple of years ago didn't use a pattern. Each round the quilter decided what to add to the quilt top. The creativity of each border that the participants sewed was part of the fun. You might like to check my album of the centers of the quilts and how they grew.
https://www.quiltingboard.com/member...bums19669.html If there is no pattern, then each person can sew at their own skill level.