I would move stuff around constantly to level it up.

Cover was always combined with hypers to get character's their limit breaks leveled up, for example.

If someone had a double or triple growth item, and I wanted to master a piece of materia to get more, I'd put it on that person and grind.

The only thing was giving physical characters materia to enhance their abilities, and strong magic characters the same.

I had no qualms about constantly moving things around.