Assuming you have a creative, a project manager, delivery manager, and a sales manager in the agency, each task/project has to go through each of their hands.

That's an hour each for the managers and how ever many hours for the actual work itself as the base delivery price. Then the internal back and forth between the delivery manager and the creative to insure that everything is "to spec". Then the project manager to report on status each day and the sales manager to take you to lunch and discuss the how amazing everything is with the project, and that the BEST people are working on it.

So 3-4 hours of work can turn into 20 hours of billing (plus expenses).

I also know they want all the work you can throw at them, but just getting a sense of whether this is a 1 hour or 5 hour gig so I can evaluate the ROI before briefing it in is impossible.

This is one of the things I want to address (my side-gig doing marketing consultancy) - one rate, whether that's strategy or design work, up to the client how to use it (and telling them to use someone else if not good value).

Different companies are wildly more efficient per hour of work never mind that many just do much better work.

Rates are kind of ethereal. Maybe they are padding. Maybe they are just slow. Maybe they are throwing several resources on it. I don't know.

This is a big problem with procurement. People fixate on hourly costs and not total cost of project.