What I have learned about watering, is that as soon as you do so, it will rain, LOL!
But seriously, I ran my watering hose (with Rain Wand attached) into a watering can, and counted. Based upon my water pressure, if I count to a slow ‘8’ Each tomato or pepper plant will get about 1/2 gallon of water with each ‘8’- count. For flowers and other things, I use a ‘4’ -count.
Does that make sense?
It’s not scientific by any means, but that amount of water, coupled with the straw mulch I use, keeps the soil moist enough for quite a few days, depending upon the heat or if it is super-windy. The mulch makes all the difference in my soil moisture, though.
I could use a nozzle pressurized by the tank sprayer now but wanted to get my feet wet with drip irrigation. LOL
Hardly any wind, ground is moist, fairly cool. I'm going out to work on high tunnel trusses.

This first one is now sitting on some new saw horses I made last week because making this one on the trailer was a major pain in the ... back.
When it gets hot or I get tired, I'm coming back in and putting Home Assistant OS on an old laptop(for now) to run this little relay/switch that will turn the drip pump on/off. Relay should be here by Fri and I have next weekend off to play with it. Might get two of those 275 gallon IBC tanks by then so I can use one just for the garden and quit using up our house water. LOL

These things are cool. They'll run from 12 vdc, 24-48 vdc or 120/240 ac and switch on/off the same variety of voltages. Lot of people use them to turn regular light switches or outlets into SMART things. I'll be using them to open/close high tunnel vents and drop down sides based on temperature inside the tunnel. I also want to get an anemometer so I can mostly close the vents/sides if it gets real windy. Gotta have automation since I work 12 hour days. As of this morning, 2,000 houses were still without power from the storms we had two days ago. Was 5,000 or 27% of the county.
Everything in the high tunnel will be 12 vdc and I have some 12 vdc based solar panels sitting here. Just need new batteries and a charge controller. The tunnel will be off grid and automated.
I don't want to come home to cooked tunnel veggies because we lost power.
12 vdc gearmotor(low rpm, high torque) for operating the vents and sides. Pulls 5.9 amps and the little blue relays can handle 10 amps.

RV pumps are 12 vdc. Aftermarket car/truck electric cooling fans are 12vdc and move a lot of of air. Small form factor computers are DC but not 12 volt(5 or 19 vdc) so I'll have to address that with a DC/DC converter. I see one for $12.