One-Shot Volume Numbers

Weird. I just noticed that this post has no content. Must be slipping in my old age...

Anywho... I noticed in my travels throughout this site & in attempts to edit the occasional page, I've come across one-shots that have no volume numbers. For instance... Shazam!

DC has published 5 separate volumes of Shazam!

https://comicvine.gamespot.com/shazam/4050-2622/
https://comicvine.gamespot.com/shazam/4050-38615/
https://comicvine.gamespot.com/shazam/4050-115760/
https://comicvine.gamespot.com/shazam/4050-137674/
https://comicvine.gamespot.com/shazam/4050-150016/

The 2nd volume is a one-shot & does not include a volume number. I can't recall if I attempted to edit this in the past & it may have been denied. Once again, old age may be stepping in...

Shouldn't this be considered as volume 2? If not, why not?

It could be argued that in the Shazam example none should have the volume tag, as the volumes are not connected and the indicia does not have volume in it. Only the first one: Shazam! has, and there the indicia goes from volume 1 to vol 6 in one volume.

Aspen comics for example has the volume number in the indicia, and the story is continuous, so reading order matters.