You don't need to set an object global to use it in another layout. I've seen it recommended against doing so for visible objects, somewhere around here, and it's good advice I think.
Global makes the instances of the object exist in all layouts - whether they have been placed in Construct or spawned.
Such as when I accidentally had some arrows set global, when I changed layouts I'd still see them placed at the same X/Y positions, which is definitely not what I intended.
Copying and pasting non-global objects to other layouts works fine, though. The same event sheets will work on those, as pasting to another layout doesn't make a brand-new.. um.. clone. They'll have the same object ID (if I'm not all mistaken about how this works).