I have a feeling that I posted this somewhere else, but I'm not sure so here goes...
I was raised with dinner at EXACTLY 6:00; sitting in your chair, butt planted. If you were one second late it was a major infraction. Best to be early. I missed it once only and was grounded for a week.
That did not apply with my own kids. We ate when we were hungry.
Years later, after my dad's death, I was talking with my mom about the rule and she told me that it was really made to make sure that Dad would get home on time from the bar after work. It was successful.