If you have very sandy soil, a drip system may not be the best solution because the water will not spread around the root ball but drains away quickly instead.  In this case you will have to continue with overhead watering or hand watering the individual plants if you have the time and inclination.   Drip systems work well with normal or clay soils. Many native and drought tolerant plants do not like to have warm wet roots in summertime.  Water early in the morning, but try not to water at all during heatwaves unless unusually prolonged.  If a heatwave is forecast, water the day before so that your plants can take up the water and protect themselves.