Anime / Manga - .........

Nah, I remember he tries to threaten the guys working on some pipes with it and he just looks like an idiot to them.

I think it's more about if the stand has a permanent state or not. Like Tohth is always that book, and Strength makes a lifeboat into a full sized tanker, whereas Emperor is conjured like other stands.
Or there is no rule because Araki is like that.