Absolutely agree Will.
I had better offers from BMW for my own VW and vice versa going the other way, plus similar experiences over the years with other marques. VW to VW is far from guaranteed to be the best price. Every case is different plus you have the option of Motorway and that ilk of trade buyer although I found in my part of the world Motorway didn’t offer very good prices even though the cars had no finance owing on them.
As you say, covering as many options as possible takes little time but opens up a better spread of potential suitors for your outgoing car.