What do you prototype?
The urge to provide quicker and quicker turnaround can result in sketchy work—but creating a quick sketch can be good. Think about prototyping your next assignment. Give them what they want in the end, but in the beginning give them a rough draft of what to expect.
Prototyping allows for change. You can work with the client in lockstep, develop the desired copy not only to specification, but to ongoing revised specs as well.
Take a page from computer software prototyping, and be both the first with the right answer, and the one who goes the distance and provides every nuance the client wants—in revisions.