Just like climbing a mountain: eventually you look up and there is nothing left to fillet, no more parts to attach with thickened epoxy, and no more epoxy coats! I still have epoxy left, probably because storage box comes with more than it required, and I was pretty careful about not over-mixing batches.
I will probably still need a few squirts to coat the electrical cutouts in the bulkhead, but that should be my last mix, knock on wood.