To write or from start to final layout?
Exactly what I was wondering.
Also, what kind of "adventure" are we talking about here? 8 pages? 16? 32?
I can sit down and in a single afternoon/couple of hours write an "adventure." Pick a storyline, a goal, a few story-relevant encounters, a few more non-story related encounters for fun/flavor, sketch out a map of the adventure area. Poof. Done. Is it ready for publication? No. Certainly not. But it would be playable.
One of my jobs is layout editor for a magazien that publishes every other month. Over the years it has run the gamut from 32 to 64 pages and back again. The past year or two, it has been fairly stable at 32 pages.
All told, laying out the magazine takes me about a "week". That is, a few hours a few days...probably not totally any more than 20 or 25 hours. That is JUST for layout and photo/image formatting.
There are are at least 2 rounds of editing/copy-editing/proofreading. So I'll wager, probably 10-15 hours for that...again, completely dependent on the length/amount of material that has to be read/edited.
Now, granted, in a published module, you don't have to worry about fitting in "advertising/-sers" and your amount of art, most likely, is significantly less than a magazine with 12-15 articles/stories and various recurrring columns.
That said, art is (imho) a
necessary (and oftentimes underutilized) consideration for published modules. Even if it is just getting a decent/evocative cover image and a few black n' whites for a couple of interior scenes and/or NPCs. And, of course, at least one map (probably 2 or 3). So acquiring that, even with a devoted artist/cartographer/art staff takes time. You are
easily looking at a week, maybe two, for a couple of maps, a cover (and, hopefully, a small back cover slice like the old TSR modules...just cuz I think it's cool to highlight an additional possible scene within the adventure) and a few (let's say even, only, 4!) black n' whites.
Working on an assumed 16 pages (including the exterior and interior covers, so only 12 pages of actual adventure text)...Overall length to prepare an adventure, completely, for publication, I am going to estimate (again, completely dependent on the length of the text)...you would need, to put/pull all of that together: written, edited, laid out, maps and art...in a decent/acceptable to you (the author/publisher) file to send off to a printer...a solid month worth of 20-ish hour weeks. Perhaps less if this is a primary "job"/40 hour per week scenario.
Of course, it also goes to how much of a perfectionist and/or nit-picker you are...how often you make (or just plain
want) changes before the final file is done. One
could spend an entire month with all of the elements just futzing around...That's why you need a GOOOOD layout editor

to just pull it all together and know when to say "I think we're done."
Just my two publishing coppers.
--Steel Dragons