with these highly concentrated flavors if you are trying to hit a target of 2.5% and you are mixing flavors (like raspberry and vanilla) do you add both flavors so that they add up to 2.5% or do you do the main one at 2.5% and then add the others on top?
Not to be discouraging, but my guess is that this question is unanswerable. Sort of like asking a chef a wide open question like "If I want to make dinner, how much oregano and how much marjoram should I use, and what temperature should I set the oven to?". He'll probably come back to you with something like "Uh..., so what are you trying to make?".
I don't mean to be a wise ..., just saying it's probably tricky to answer your question in such general terms. I don't have the hang of this myself, but absent a specific recipe you're shooting for I'm not sure anyone can steer you effectively, and I doubt there are many recipes for these VZ super concentrates because they're so new.
My approach so far is to just mix individual batches of each flavor separately to my taste for each flavor. When I want to see how a combination of flavors taste together, I combine portions of those pre-made batches in a separate small batch to try to get a general ratio down. My plan(fingers crossed) is that when I have something that seems to be generally heading in the right direction, only then will I worry about tweaking individual flavors in that combination so that they're at a higher or lower % than I would use if I were
vaping those same flavors standalone. That's how I was naively planning on approaching it anyway. I'm new to this too.