We've been about four times inthe last few years. I'd say between an hour and an hour and half is about correct for the average dinner. More, if you include your actual ADR and happen to have to wait past it a bit. (some times you get seated very close to your ADR, and sometimes you have to wait for a table to open up.)
Incidentally, we had rather bad experience at the Poly sushi bar on our last trip. There was one server for the entire area (seats along the sushi bar and along the window.) The system was really odd, and "the computer was down" part of the time. We almost gave up on getting our food, but the sushi was quite good. It would have been nicer if the whole meal had been quite a bit faster though.
Beyond that, the bathrooms in that area were disgusting during our last 'Ohana visit (August). Paper everywhere, water everywhere, soap all over. Nothing truly foul, but they obviously had not been serviced in some time. The family restroom was even worse. I would never expect to see such a thing in a resort that expensive. They have always been clean in the past. I walked in before our meal and then decided I could wait.(they were that bad.) After our meal (so at least an hour later), I tried again. They had not been serviced. While I was in there though, someone finally came to clean them. I felt bad for her, they were really dirty.