There are a bunch of little questions in the OP that mostly equate to an answer of "maybe".
The good news is that it is really easy to find out if your maybe leans toward yes or toward no. The next time you mix a tank's worth of juice, make two and set the second one aside with a label containing the flavor and date. Do this for each flavor you make in a week's time.
Then after a label's date is a few weeks in the past, fill a tank with it and try it.
Unless you mistakenly left the top off and/or left the bottle in the sun, I doubt there will be any TH difference, but the rest might change. If you pull that set-aside-bottle out of it's dark drawer and notice the juice is darker than it usually is when you first fill your tank, I'll bet the taste has changed.
I have recipes that need to steep to get the full effect of all the tastes. I have recipes that do not get any benefit from steeping. I have recipes that are good to go from the moment they are mixed, but change flavor when steeped and I like both the fresh and the steeped tastes. There is only one way to find out, try it.
(Thanks for the kind words Rimau.)