I flew the LAX-DTW redeye on Friday. (I was #8 for two available upgrade seats, but that's my irrelevant whine.) The "buckle-seat belt logo" signs remained on the entire flight.

At take-off, we got two announcements. An FA said, "Please observe the buckle seat belt signs. They will remain "on" as until the pilot thinks it is safe to get up"

Pilot says, "We expect a smooth ride, except for some turbulence mid-flight".

My complaint is that with a plane load of people, some are going to have to use the bathroom during a four-hour flight. The flight was a smooth one. I think the pilot should use common sense, and turn off the sign after take-off so long as there isn't turbulence.