I Usually vape 2-3 smoky flavours and change them when i get used to a spcific e-juice taste.
Now i vape a lot of e-juice 6-8 ml /day .
On my 2nd favourite rta though i have left e-juice for even 2-3 weeks.
The color changes through oxidization ofc.
Well steeping requires that both aroma and base are into tank and if you consider that aroma is lighter than base then most probably if the e-juice are not already steeped you may have a lot of aroma on RTA.
Another interesting point is that on some e-juice brands the longer the e-juice steeps the better the e-liquid will be,
but on some other e-juice brands after let's say a week the e-juice is ready to vape but after a month of steeping the e-juice tastes differently so differently that usually ends in waste basket or sink