"I've read that there's a lot of (especially large) firms out there,
utilizing Revit and ADT in this fashion."
We've got some like that. Some are also 100% Revit...
"I wonder if this has anything to do with the current shortage of proficient Revit production-level workforce?"
It has everything to do with that. The big projects we got going on Revit that are also using ADT for the CD's is because of team, training, and time demands. If those teams were ready to hit the ground running on a huge project, we'd probably be 100% Revit on those jobs.
But as it is now, we've got a handful of folks that are up to speed to that level, so we do some stuff in Revit, some stuff in ADT, and get a lot of bang for our buck in the short term for these big projects. Other projects we got going are 100% Revit. It really depends on the team, training time, ect...
"I imagine higher level Designers conceive the lan/section/elevation in Revit, and then turn the design over to an ADT production staff; much like the traditional hand-sketch/drafted document relationship."
While that is a viable method, and there are some larger firms that do just this, I don't see it really being necessary. Personally. You don't gain much switching systems mid-swing, and you can totally do Cd's in Revit pretty efficiently. Well, that is, until Autodesk makes something that lets you move between the two systems better. Then maybe. But even then I don't see much gained, unless your office's people are really that much more efficient on ADT. But if ADT is really that much better and faster than Revit when it comes to CD's, then why are folks using Revit for CD's?
"Maybe, in the future, as the Revit trained workforce expands; this 'hand-off' may not be as necessary?"
It's not 'necessary' now, actually. It's just timing and level of experience, really...
Jeffrey