I'll just try to clarify one point you mention. Each club can have one spec applied but if say you win/buy an iron spec then you are able to apply this to all of your irons. You do need to do this individually for each iron though.
As for whether the specs are having the intended effect, a video showing what differences you are/aren't seeing would probably be helpful.
I am having the same issue. I open each iron, apply the spec. When I do this it removes from the previous iron. I am not able to put it on more than one club.
