Not sure, I would start with an hour, but less might be enough.

My God, and you've been in the museum with her for hours some days.

All our systems died with an hour or so still left in the wait.

He must have done with no more than three or four hours sleep.

"And if a minute not taken now means having to pay with an hour or a day later on?"

The house is now open to the public, with limited hours.

"But what am I going to do with two hours a week?"

That left him with two or three hours' worth per day.

Second, even with many hours of screen time, you can't include everyone and everything.

Even with her doctor's hours, he was usually the first one to rise.