With the introduction of "refinements" & "doubles" quite some time ago, the game dynamics were considerably altered. Studio challenges have become a case of "how many diamonds one is prepared to spend" rather than how well are studio members motivated to "progress and participate".
While this is good for the game promoters and "refinements" admittedly do add to the interest (and 1 free go is provided per day), "doubles" have killed the original "collaborative spirit" within studios. Studio members no longer need to be a well-knit "team" but can be a bunch of dummies, compensated for by their doubles!
If the promoters insist on maintaining this feature (which they no doubt will since it earns them purchased diamonds), to provide at least some enjoyment along the lines before this changed dynamic was introduced, doubles should only count 75% (still more than a non-participant) but NOT 100%!
Hopefully one of the Moderators will see that a developer gets to read this.