I split and stacked 10 cord of red oak this spring. Top covered half. The other half did not cover at all wide open to the elements. The top covered half is around 39% consistently testing fresh splits with a moisture meter. The uncovered cords (just rained for several hours couple days ago) was around 29%. Both sit beside each other and are subject to the same wind and sun. I tested several pieces in each stack and it was very consistent. I also have some pin oak covered in the same area that is two years old and it is 35%. Seems pretty clear to me that uncovering is the way to go at least where I am. Thank god for some ash and cherry I have from two years ago this oak will not be ready for at least two more seasons.