I think the biggest farce in the idea of "steeping" is that people believe that the flavors are changing. I honestly don't believe this to be the case. I don't believe that if I mix Flavor A into VG that it will change chemical composition, and transform into a different (albeit) similar more desirable flavor. It makes no sense.
What I believe to be happening in the process is allowing the ingredients to settle.
If I mix a flavor into a base, no matter how much I shake it, it won't blend as well as it would if I just left it alone for a given amount of time (i.e. 24 hours) + the initial shake. I imagine it in my head as the flavor molecules needed extra time to reach the all of the unaffected molecules in the base (allowing the flavoring to spread out, and reach all areas of the base). As opposed to vaping right after a mix, the flavor molecules are much more condensed. This is also why I think people believe that steeping alters the flavoring, when I just believe it's diluting it further to change certain aspects of the taste, but not actually changing the flavor itself.
This is also why I believe that no amounts of steeping will change a bad flavor into a good one. Rather, it may help settle down a potent flavor (because after sitting for a little bit, the flavoring has had time to spread out further, instead of being overly condensed, i.e. potent).
This process gets even more complicated with multi-flavor blends, because it's not just one flavoring competing to reach all aspects of the base, but many. Some flavorings will spread quicker than others, and so many variables can be put into that equation. For example: People may advise someone to allow an all VG blend to sit longer than an all PG blend. I attribute this to viscosity of said base(s), and how long it takes the flavoring(s) to reach all parts of the base.
In the long run, I don't give my blends time to steep, and if I do, I certainly don't wait any longer than 48 hours, tops. This is because I don't believe that the blend will benefit from further sitting (the exception I could see to this would be homemade, or NET's, as perhaps these may take longer to spread, or settle. I cannot say personally, because I've never tried one.)
I try my blend as soon as I mix it. If it tastes great, I vape it. If it tastes good, but feels like it's too powerful, or lacking, I'll give it the night. If it's no good beyond that, it usually goes into the Abyss (100ml big bottle of mistakes).
Just my thoughts on the matter.