Just a quick anecdote: one client I have has decided to use Agile Work to develop the user stories as part of a large project they are embarking upon.
In this meta-project, their team is composed of analysts and some technical people (although not everyone who will be on the development team).
The items in their Work Queue are large functional areas that have been identified. Each functional area could be thought of as a mega-epic which needs to be developed into epics and user stories.
They are using short iterations (I think 2 weeks long) and working on refining their user stories until they can make an estimate on the development part of the project that they are comfortable with.
“Done” for this meta-project means that the user stories are small enough, follow the simple template, and have the INVEST qualities.
At first, I tried to convince this client to do much less work on getting ready and just start the development teams. However, they quite rightly pushed back. They are doing work for a client who has agreed to pay them do develop a good set of requirements and an estimate to go along with it. Both my client and their client are aware of the advantages of early delivery of working software (their ultimate goal), but both have agreed that early delivery of good user stories in a Work Queue is also needed.