Exactly right, Eastwest Loco, for large weights. Smaller weights can be handled more flexibly, though.
Regarding large weight problems, I had to take all pax bags off to get out of Wellington for Brisbane once (ROK as only alt, 34 at WLG as tailwind too high for 16).
Bags sent to CHC to make the next flight to BNE. Made PA to that effect & had one guy say that he needed his bags, as he was connecting to LHR. Left his on & took crew bags off, to be sent to CHC only, as we were doing BNE-CHC once we got to BNE. Also told the pax in layman terms that the takeoff performance would look very good to them, but that we had to cover the engine failure senario, which was much worse.
Everybody was happy to make the flight & get their bags later in the day. As far as I am aware there was not one complaint.
Flight Ops felt that the number of seats should have been limited out of WLG for performance reasons from the get go, but commercial wouldn't listen. As most flights managed to get out over time, perhaps they were right. Big picture stuff I guess.