When creating a layout, designers put low-resolution, imperfect, non-final images, all marked "for position only." They exist to help the client understand the gestalt of the piece and to give feedback.
They're temporary, parts of a whole ready to be replaced with the real thing once the big picture is locked down.
And the concept works in just about every project, every conceptual structure we seek to put together.
We act 'as if', then we worry about the polish at the end, not at the start.