what soil do you have? do you have mulch?

Native was a sandy soil, former lawn. I added a few inches of compost from the greenery, and then another few inches of steer manure. I've had 2 good crops so far, but not with the drip.

I can get mulch cheap.

I use a drip system for my crops in my hoophouse. I look at and feel the soil to determine if it needs additional watering. I don't like automatic systems. you need to observe your crop and make the call whether or not it is needed. I don't know your climate, but I would rather deep water once a week rather than daily.

Ditto on twice-a-day watering being not good as roots generally follow the water and shallow roots are generally bad and cause stress in high heat as the upper layers dry.

Water half as often for twice as long, and after a few days get the trowel and dig down to see what's really happening to the damp/dry boundary. Only you can get you your answer.

Even daily isn't needed or good much less 2x daily. Assuming proper distribution throughout the planted area then those crops should do fine with something like 2-3 gal (30-45 mins.) once a week. But like jnfarm said you are still going to have to check your soil moisture levels 6" down and your plant appearance at least daily and adjust accordingly for your soil's drainage rate. Deep watering infrequently is always better than shallow watering frequently.

For plants in containers it would be more like what you were thinking but not for inground plants.

Dave

Drought restrictions are in place here. We can only water 3 x per week, other than trees, plants have 1/2 - 1 gallon emitters that are on for 45 minutes starting at 5 AM.

I sympathize with the OP since CA conditions are different from our Midwest. Yes, with sandy soil (2 inches of compost do not change anything, you need one foot plus to start having a bit of loam) mulch is less useful, since losses are mostly from below, and I would recommend daily watering or every second day at the most. Still, at such a site I would mulch heavily, to eventually get some OM in the soil and improve water absorption. It will still help with evaporation and improve surface roots. In fact, I would rent an excavator and make low hugelkultur beds.

I know that at my previous site, which was pure sand, watering with drip every two days was normal, and this was wet Michigan. One hour after watering, the soil was dry, and the soil 5 inches from an emitter was dry regardless. The soil there, I had to excavate around the house to do a foundation job, was bone dry to 8 feet in midsummer, so these ideas that the root need to be developed do not work in very sandy soils. I can not give further advice without knowing the plants involved, the density of planting and the density of drip.