I've been on smoothe flights where the sign was kept on practically the whole time. Unfortunately I suspect some pilots forget about it, and I have observed tha

I've been on smoothe flights where the sign was kept on practically the whole time. Unfortunately I suspect some pilots forget about it, and I have observed that the public have gotten used to getting up to use the bathroom even when the sign is on (excluding takeoff and landing). I haven't flown enough to notice a pattern with specific routes or airlines.