Guys guys guys, your comments are correct up to a point. However, much of what you say is dependent on the type and actual circumstances on the day too. May I say that if on an EMB145 or CRJ or indeed a small turboprop I don't do it. You have to convince me what difference it will make on a B737 or A319/320 on a short 1 hour hop. Why? Because if you fly on a "light" flight with Southwest (or Ryanair/Easy for that matter) it's free seating and pax spread themselves around. So how do they accurately finalise the loadsheet in these cases? I have been flying for 48 years by the way.