If I was participating - which I'm not - so perhaps I should not say anything -
I would want everyone to be using the same pattern- I just looked up "Churn Dash" in "Enclyclopedia Of Pieced Quilt Patterns" compiled by Barbara Brackman - and there were four blocks with the name of Churn Dash.
A couple of those blocks had several other names, too - so it could be confusing.
So - I am not sure how much "variety" the participants want - or are expecting.
For myself, I would prefer the blocks to be the same as far as pattern and size.