I'm an airline First Officer for a regional carrier. In my experience, the majority of Captains leave the sign on way longer than needed. I can totally see how this can make passengers numb to it. I've had several occasions where it's my leg (I'm flying) and it's totally smooth out. I might say something like "I think I'll let them up, agree?" Many Captains are hesitant and start citing "well let's leave it on a bit longer so the FA can do service." I think it seems to be a generational thing that will just have to play out.