Allowing the soil to get somewhat dry between waterings will cause the roots to spread out faster seeking moisture and that will equate to better, faster, healthier growth. Keeping it wet all the time will equate to a stunted slow growing unhealthy plant and it may eventually die from it. This is how it works outside in nature. When it rains it usually rains for a couple hrs or sometimes days. Then it usually does not rain for several days. Cycles of getting completely wet and then almost completely dry is the natural way of things and plants thrive in this type of cycle.