It really depends on how long the wood has been dead. Other than blow downs, I cut exclusively standing dead or down red oak. I have found if the standing dead oak has been dead so long that the bark has come off, a lot of the tree is ready to burn right away. I am talking about moisture contents @20% and less.
That part of the tree not ready to burn, once blocked, split and stacked will be ready to burn in a few months, not years. Trees that are on the ground dead, with bark off will sometimes be wet. Not green, wet. With the bark off, the wood is not water proof, so the tree will wick moisture from the ground. Again, once cut split and stacked it will dry incredibly fast.
You can argue this point til the cows come home, go right ahead. I am just telling you what I have learned over 30 plus years of cutting oak for firewood. Things could be different in different climates, for sure. I am just relating my findings according to the climate we have here in MN.
Ted