Media
The project-wide media gallery -- the workbench for trying a model, workflow or recipe.
A project-wide Media Gallery -- the workbench for trying out a model, a workflow or a recipe when the result is not a picture of any particular character, location, prop, scene or shot. Run something, look at it, keep what works and move on.
Everywhere else a gallery belongs to one thing, so experimenting there leaves test images sitting in that character's or shot's gallery. This is where that work belongs instead.
Trying a model straight away
The Actions tab here leads with two suggestion cards, Try a text-to-image model and Try an image-to-video model, alongside the shared Refine image and Custom actions. They are there so a model you have just downloaded can be tried immediately: run it, look at what came out, decide whether it earns a place in the show. Each card is a single step over the operation it names -- so the model is the only variable -- and it says which model it will run with. Every other action is still offered below them.
Moving work out of the workbench
Otherwise it behaves exactly like every other gallery, and it appears in the Organize action's destination tree as Project -- so you can drag a keeper across to the character or shot it turned out to suit, and drag anything from an entity gallery back here to work on it. It is also listed as Project in the Browse Media Files dialog, so a file kept here can be picked from anywhere in the project.
One limit: Link is the one transfer Organize cannot make out of this gallery. A link has to name the entity it points back at, and the workbench is not an entity -- use Copy or Move instead. (Linking into the project gallery, and browsing to a file here and linking it, both work normally.)