Noob question: 5* max sig crystal attainable if dupe at 180 or 181 sig level?

Ethereality

I know this is a noob question. Have uncountable max sig 4* stars so I should already know the answer but I have never really paid attention to whether I would get a 4* max sig crystal at 79 sig or if 80 ... so I really dont know.

So, my question stems from the fact that as a policy, I never use class or generic sig stones past 180, because although 5* sig stones are relatively easy to get these days, I still dont wanna waste them if I happen to dupe a a champ on which I've used stones to take to 200. Because of this, I have OR, Magneto, CAIW, Aegon and Guardian at 180 currently, could take them to 200 woth stones if I wanted but I wont....


...But it just struck me: Sure, if I dupe them as they are I would get them to 200 with no waste of stones but I would also lose on the chance to getting extra 6* shards through the 5* max sig crystal correct? Or am I wrong?

If so, wouldn't it be better to have them at 181 sig, so if I dupe them I would only have wasted ONE stone but would have gained more 6* shards from it?

Is my logic correct? Sorry for such a noob question.

Amneties

You only get a max sig crystal only if the champion is at max sig. Even if you dupe a 5 star that’s at sig 199, you still wouldn’t get the max sig crystal.

Ethereality

Oooh I see, so if what I want is not to waste any sig stones, then keeping them at 180 is the way to go correct?