Ask Mr. Smarty Plants

Newly planted plants should be watered only enough to prevent "flagging".  That is when the plant goes limp and bends over but bounces back when watered.  If a leaf or plant part wilts, it will often recover but if dries out enough to be crackly ... it's a goner.

You will have to be the judge of how often is enough as it depends on a number of factors such as: how strong the sunlight is, how quickly the soil dries and how much rain you are getting.  Although you would think that sprinklers are the same as rain, they are not and you are wise to avoid using them, if at all practical, for the reason you are wondering about.  Too much sprinkling promotes the growth of molds, fungi and diseases.

The plants will do best if they can take the water they need from the soil.  That means that ideally, you should hand water each plant, but around its base, not directly on it.  It is a good idea to put your hand into the soil under the leaves around the plant to feel how much moisture is in the soil before watering it.  If the soil is still moist, wait until it is a little drier.  You want the plant to develop deep roots that will reach down for moisture.