Thanks for all your comments. I think I have a better understanding now. I usually like to be in control, know what the ending will be and so look forward to mystery quilts where I have no control. I just thought if you were doing a mystery quilt, you had to follow the directions exactly. Silly me!
When I taught a mystery quilt this summer at our quilt camp, I taught the block and the "mystery" was how to put the block together once I taught the layout and technique of the block. Since there were several different designs (as there often are), the "mystery" was solving how they would put theirs together. So each solved it their way . Wonder why I didn't think of the BH mystery !