SE suspension answer
To the original question, a faster rebound clicker setting (more open), will likely improve the function over tightly spaced washboard by allowing the shock to recover before it encounters the next bump. a shocks inability to do this is what is commonly referred to as "packing"
The 17mm nut outside the shocks compression clicker is what is called the "high speed" compression adjuster. It is a bit of a misnomer, as real high speed movements are more regulated by the compression stack inside the shock.
The high speed adjuster actually increases or reduces spring preload against a miniature stack that is contained within the compression adjuster itself. This allows the bleed circuit to either hang in for longer or be overcome more easily, thus making it an adjuster for the adjuster if you will.
In practical application it works as sort of a dynamic ride height adjuster, either resisting or allowing squat to the rear.
Hope that helps, I find understanding the mechanism often help make understanding its function much clearer.
Never argue with stupid people, they will drag you down to their level and beat you with experience.