The way we have scrolls dropping is actually consistent with live in this regard except that on live they have certain mobs with a greater chance to drop specific scrolls and otherwise is a little more random as you don't kill different things for 1, 2 and 3 like in our system.
Live has gone a few ways with scrolls.
Early on it was you had 3 different mobs that drop a particular scroll, it was not always a mob in the EXACT zone of the artifact. Example Egg of Youth scrolls drop from the fish people mobs, Naxos Sentinels for Egg of youth 1 yet that encounter is in Notos. This IMO was a very frustrating system for getting certain arti scrolls because the mobs were scarce or pain in the butt to farm. Example on Gaheris a must have arti was Snatchers (for the rp boost since we only had to wear it when turning in seals) and those scrolls drop off purple taur, thus not very farmable solo for many people.
That system was in for quite some time until they moved to a system wear scrolls droped based on the zone region of the arti, and was completely random.
Then not long after that they added an increased drop chance on the mobs that use to drop them in the early system. This way you have a lot of freedom to farm in general for scrolls but if you want to up you chances for a specific scroll you farm it.
Mythic does not break scrolls drops down to specific zone and I see no reason for us to do so, though I wouldn't hurt to add the increased chance for scrolls on certain mobs but it probably be a bit of work that can be better spent on other things.
Edit:
Just wanted to add link to Mythic herald patch regard scroll drops:
http://www.camelotherald.com/news/news_ ... oryid=2289
In my experience that "increased" chance isn't huge, I could usually get the scroll associated with that particular mob within an hour but I would also farm up an inventory worth or more of other assorted scrolls.