The Crystal Ball has very little text - it requires attunement, and anyone attuned can cast Scrying with a set DC while touching it. Obviously, this has limitations, such as when Scrying fails, you can't scry on that person for 24 hours! But someone else can...
What if my helpers each attune to my Crystal Ball to use it after I fail to scry on an Ancient Gold Dragon? It has legendary resistance, so it's actually impossible to scry on with the first try without attacking the dragon first or something else.
Can we do this 24 (or 25, I haven't checked) times before the next day on the same person, or will something stop us besides the Scrying spell, like attunement or magic item rules?