My turn to chime in 
After reading everything JP posted about the subject last season...i had to try it! Why?,because it seemed alot easier to try for my first incubation attempts than hand judging vermiculite moisture levels.
All eleven of my first two clutches ever hatched out just fine last year(without a fan even!..lucky?,perhaps.)

More than that...Before i had finally got the boxes set up.Three of the eggs in the first clutch had become waterlogged from my "temporary igloo-bator eggbox"(You can see the water marks on the eggs in the pic),AND two of the others were dehydrated.
(The second clutch of three were fortunate enough to go straight into a no-sub box.)
So this method has proven to me to be absolutely idiot proof! 
Much thanks to you JP!
-----
Charles Glaspie
Tanstaafl:
"There ain't no such thing as a free lunch".
An acronym created by my favorite author Robert A. Heinlein.