If your standard deviation is that high, I would first try to eliminate all factors that could cause variability. "Reverse engineering" as Ingo puts is a good start. I suspect a lot of people will be shocked to see actual wet variation!
Always start with the basics: dimensions, air flow, heat distribution. A simple thing like one vent opening slightly more or less than the next vent on the same kiln can do funny things to air flow, energy transfer and final moisture content. Even many steps with big jumps can result in greater MC% variability.
If the basics are right and your schedule is optimal...equalizing and conditioning should (almost) not be necessary.