Heavy clay soil also here. One thing about clay is it slow to dry out and slow to moisten back up, of course depending on the amount of amendment that might change. If I have regular rains I don't water at all. I wait until the plants begin to show signs of being too dry such as the tops beginning to wilt a bit during the hottest part of the day, then I water very deeply, probably an hour or so for each row with a soaker hose.

We were using a drip system, every day for 30 min and just switched to every other day for an hour.

Drip tape or inline drippers? What GPH are your drippers? I can't imagine why the plants would have to be watered daily or even every other day but only 30 mins. on a drip system isn't long at all. Unless you are running 3 or 4 gph drippers it is very shallow watering. If using drip tape instead what is the hole spacing on the tape That determines how long to run it.

My inline drippers are 1 gph and I water once every week if no rain and every 10-12 days depending on any rain we got. But my system runs for 2 1/2-3 hours at a time until I can stick my hand deep into the soil and feel the moisture at a good 6-8" down. That is deep watering.

It takes a long time for drip irrigation to deliver much water.

Dave

It's hard to make a schedule for watering. You have to
adjust depending on the local conditions and soil type.

Your goal should be consistent moisture at the root zone.

How you achieve that is the problem. One week might
be sunny, windy and dry and the next week overcast and no wind.

Check your soil and make the necessary adjustments to
keep it moist.

I'm in CA with caliche soil (heavily amended) Caliche will
turn into a brick in a day or two. I'm constantly checking
the soil and watering as needed.