You hit the nail on the head. You can't overwater a well draining pot and medium. The problems and deficiencies come into play when you water too often, displacing air pockets with water, keeping the roots in a saturated environment, denying their ability to respire effectively. Sure they take oxygen from the water, but not enough to function properly. They require those air pockets.Can u overwatter if u watter a plant with plenty water but then u wait until the soil os dry? And water again? Is overwattering more about how often do u water and not how much?