depends. the cheapo roncos aren't it. They lack a fan, require moving the racks around and zero control of the temp.
Typically the dehydrators get frowned upon because most run too hot. My Excalibur unit only goes as low as 85F. Cut out the heater, and its only a fan dried box, not going to decrease the dry time much. Too much heat and the the THC starts to breakdown.
A more natural dry time usually leads to a better tasting bud.
As the old saying goes, haste makes waste.
BTW, I've never used it to dry weed.