If you do a quilt where you start with a center medallion, which is usually 18"x18" or larger, then add rows around the center, it is called a round robin. You can also do a row robin, which is where you make a row of blocks, then pass it to the next person until everyone has made a row. I belonged to a bee that did this. We specified 6 - 9" finished blocks or 9 - 6" finished blocks so the rows would come out the same size. We had one month to finish our row, then we passed the row to the next person on the list. We had 12 people, so it took us a year for everyone to make their row, then we gave ourselves two months to sew the rows into a top.
If you want to do friendship blocks, I would consider a block exchange with a larger block, since there are only 6 of you. Each person would make 6 of the same block and would sign each one. Then you would get together and each person would get one of the other 5 blocks. If you made them 12" finished, you could then make 6 spacer blocks, then sash the blocks to make your top.