It can be frustrating when Station 0 isn't where you think it should be. In my experience, STA 0 may be tied to something like a location on the launch pad/launch rail. That way the ground segment and flight segment stations match. Even more frustrating than having to account for an oddball STA 0 when dimensioning a model is having the flight and ground segments use completely different stations when you need to work with both. You have to be aware there IS an offset (not always obvious when looking at a drawing of one or the other), and you have to know the magnitude (conversion factor, if you like) of the offset. Far easier when everything is made to align!