In addition to what was asked I sometimes use graph collections: I created one “general purpose” collection and then add various graphs to that collection (e.g. metric X from host A and metric Y from host B) to see them on one page and examine how they affect each other or whatever.
Once I’m done, I remove the graphs from that collection but keep the collection itself, as a temporary storage space, so to say.
So custom graphs are not so important to me, but graph collections are.