This is my first toon to get my 50/50 elites and I want to try to be efficient while I get the items...Is it possible to gather say, 6/3 Infernal Blackhorns on the first attempt for your main class? I know you need only 3/3 for the quest, but can you gather the extra three while doing it the first time to save time trying to get them again on your secondary class? If so, does this work for all the items for all the quests in the 50/50 elite chain?
Yes/No.. depends really. I am personally working on these now so I can only give what my experiecnes are. I do gather the parts for doing both quests for both sides at the same time so to speak, but when I do get the 3 blackhorns (since you made reference to this) I put those 3 parts in the bank and then go get the other 3 that I need for the quest. I "believe" that once you have all of the quest pieces they don't drop anymore, then again some of it is random luck and well I don't have the best of luck so it might work just fine as long as you have the quest.
edit: I also found when i needed to get the ice/fire magic (I think that's the right name) I can just use the same mob multiple times to get the part. Assuming of course I have enough of the item to do that.
Also FYI incase you didn't know. Doing the quest a 2nd time is considered a daily so if you don't see the quest being offered it's because your dailys are already done for the day. Same principle if you have the quest done but can't turn it in yet.