I'm trying to learn how to dry blanks in a kiln. I've done two loads so far, and they have had the end grain sealed before putting them in the kiln. My kiln is so small, it's only been taking a couple of weeks or less to get the wood down to < 20% moisture (according to my el-cheapo moisture meter.) That may be too fast for the type of woods that I've been drying - maple and walnut - because I've had some cracking. If I can learn this process, I'll have turning blanks in shorter time than sealing and storing, but I'm still learning.
I guess a simpler answer would be, seal your endgrain no matter what.