Once a day watering is usually enough, but it's better to judge by how wet the sod is. Sod should be damp, like a wrung-out sponge. Not wet, soaked, drenched, dry, or so on. Just damp at all times for the first few weeks.

I can't really tell, but that looks a bit too wet to me, and that will tend to drown the roots and wash all the resources out of the soil. Backing off a little will stop that from happening, and a little bit of a gentle feeding won't be a problem, either.

You didn't mention your locale, but that looks like you're somewhere warm.

It appears to be St Augustine turf. Would you kindly tell us where you live?

It's beyond too wet. 20 minutes was too long to water especially 2x per day. Now it has a fungal disease. I would scamper to my nearest feed store to pick up a bag of ordinary whole ground corn meal. Spread it at a rate of 20 pounds per 1,000 square feet and hope for the best. This is not the best time of year to be getting rid of disease, so remember the corn meal in April, 2021.

It is very odd that the roots have not penetrated to the soil. Did the installers roll the sod down? If not it is not too late to walk on the sod. But if the soil feels squishy under your feet, stop immediately and let it dry out. Roots will not grow through the air to get to the moist soil underneath, so the bottom of the sod needs to be in contact with the top of the soil. You might need to skip several days of watering for the wet soil to dry out enough to walk on.