I found that unless one is asleep at the wheel they can prevent transmission gear hunting. Then prevent over heating their transmission.
If I do not want or need engine braking then Staying in OD is not going to cause gear hunting.
Climbing a grade at 70 and the trans down shifts from OD into D. By just by keeping your truck at 60 or 65 (depending on the steepness of the grade) the trans will not upshift back into OD. Thus no gear hunting is done.
If you must do 70 up that grade and the auto downshifts from OD to D, you then move the shift selector from OD to D then apply the gas until you hit 70. Also by moving the shift lever you are not down shifting the trans out of OD. The automatic trans already did that. By moving the shift lever into drive you are preventing the transmission from up shifting, which is you preventing gear hunting.