The idea that all (or most eliquids) are better with age is very subjective. The mind plays wonderful tricks on us.
I am the kind of guy that is not swayed by general opinion or unscientific theory, I make mine fresh, it's how I feel it is best, what is done after is not my concern But at least people know they start off "new".
In my opinion, you shake really vigorously, you're done, it will never taste as good as the first day.
This is just me, others feel differently. And there is a really easy way to tell, get a liquid, try it first day, rate it, try it again in a week, repeat and review. if steeping works for your taste buds, awesome, if not, awesome.
as far as itchy hives, if one starts thinking this way they will never vape, an itch here, a breakout there, it's not automatically a vape liquid. I caution anyone going own that road... ever get an Ant on you and then for the rest of the day you feel them crawling on you? It's like that. Don't let itchy rash=bad liquid
I bet many of you are itchy right now
LOL (how many of you just scratched?)