my travel has been reduced to dca-dfw-dca. us & aa do the nonstops.
on aa, somewhere in the range of 15-20 min after takeoff and before landing, the seatbelt sign is turned off.
on us, the light goes off after 90 min, and back on 60 min before landing(flight is 2.5-3hrs). everybody gets up and "feel(s) free to move about the plane" as soon as we get past the white house.
the seatbelt sign is some form of a government reg, and violating that light is a few years of hard time in a cuban resort with all the water you want, and then some.