Well, I've never been inside the Dickel plant, but to my knowledge they steep the char. I may be incorrect, of course.
I would also think that the proof of the new make would have an effect as it related to extracting wood compounds. Do JD and Dickel introduce the whiskey to the char at the same proof?
It is one of my favorite spirits to make. The white dog, to my taste, is simply awful and out of balance. But if you let those phenols that come from charring the maple oxidize and blend with the barrel sugars, you've really got an interesting whiskey.
Not surprisingly, I'm quite fond of JD and Dickel. There's more going on in those whiskies than some give credit, IMHO.