While, admittedly, it was Moore's and Gaiman's stories that pretty much led to the creation of Vertigo, I do find it interesting how much people forget that the early run of Moore's "Swamp Thing" was "mainstream DCU". Heck, Constantine appeared in CoIE - even was one of the people summoned to the Monitor's HQ and was part of the occult forces - and the "businessman Luthor" had that great Swamp Thing appearance (where he pulls a Howard Hughes, charging a million or so for 15 minutes of his time during which he scribbled down on a napkin the solution for those hiring - which was to destroy Swamp Thing; before folks say the buyers were gypped, the plan worked and for all intents Swamp Thing was killed and only survived by his consciousness heading off to another part of the universe and him struggling for a long time to return to Earth).

Even the interesting relationship between Zee and John first appeared in normal DCU (during the "American Gothic" storyline, Zatara wasn't thrilled to see Zatanna's old tantic sex boyfriend which made later events between the three extra interesting).

That said, I wish they would continue publishing "Hellblazer". No reason there can't be two doses of Constantine each month.

Particularly with how Marvel seems to manage two or three Punisher series at a time and some falling outside the main universe (MAX).

I'd argue that with the exception of Ellis and Milligan's stories, Constantine didn't age in real time.

Prior to Ellis' 40 story, he was as indeterminately mature as any serial adventure hero. No one was making a big deal about his age or about him getting any older. In terms of aging, I don't really remember any other stories (other than the oddball stories set in the future) referring to him getting older after that 40 story until Milligan came along.

Feel free to remind me about the ones I have inevitably forgotten.

I suspect that once Ellis wrote that issue featuring the landmark birthday, the aging of the character was no longer relevant. Later writers, to the best of my memory also left it alone.

That's why I see the aging-in-real-time schtick as something peculiar to Milligan. It wasn't just a one-off mention. Constantine's advancing age is a particular hallmark of this run.

It may seem like heresy, but Garth Ennis killed Hellblazer for me.

It's my understanding that they've halted Punisher MAX, FWIW

Ennis wrote the 40th birthday party, not Ellis. Off the top of my head, the Aaron two-parter in particular sticks with the aging in real time conceit, as it centers on someone making a doc about Mucous Membrane, with the time the band was active still firmly set in the late 70s. Even more notably, there's how Gemma's grown up over the course of the series (see Carey for that, not just Milligan).

I suppose you could say it's been more important to come writers than others, but as far as I can recall, none of them ever went against it and there was never any sliding time-scale.