Saving time and water.  Beds 1 and 2 are installed with drip lines.  Soon they will be buried under the mulch so the water percolates into the soil better.  The 3 inches of mulch has been working great to reduce evaporation but it soaks up a lot of water when it is sprayed with a hose.  The downside of drip lines; a bit more maintenance, more cost, and the tendency to pay less attention to the plants.  The freedom from watering with a hose and using less water definitely have tradeoffs, but in terms of water use, it is totally worth it.