Agree all can be guilty of that. But when your in "the...

Agree all can be guilty of that. But when your in "the assumptions" business, and I have worked, trained and mentored others, it is of paramount importance to have a sound understanding, with appropriate research, of the basis of your assumptions. I would tell the juniors if you don't know then flip a coin, heads or tails, and be ready to have strips torn off your body when someone questions your assumptions, at least you have 50/50 chance of being right. My message got across .
Most people accept that assumptions can be wrong, its the workings arriving at the assumptions which can lead to constructive debate or discussion.

And yes, normally how the payment system works for FOB (free on board), however I believe Core sold DSO, as CIF (inclusive of customns, insurance and freight costs) to the customers door (figuratively speaking). As a customer I would not be making final payment until it arrived.

(Umm might need to check if CIF or FOB, relying on memory here )