every order i've received of BB or GJ always tastes a bit different anyways
That's because he has customers like Wingnut telling him that mixing by the bottle is better.
Monster - why must you make this a personal attack? Do you think that Ben is awaiting instructions from Wingnut, and will not move forward until he is given the okay?
I understand that your issue is with the idea, so, no issue in making it personal.
And, to answer the other statement: Without hearing it from the Man himself, I have it under firm belief that their tobacco blends are made with a tobacco extract. If this is the case, then yes, it wouldn't be surprising to sometimes experience a minor difference in taste every now and again.
Now, let me give my opinion as to why it's an issue to make 15,000mls before orders are placed. In fact, it can be simply explained with one word, ingredients.
If Ben et al. pre-made all of their juices, in set amounts, there could be a possible inconsistency in the ability to have your own personal preferred nic-strength, or even your preferred juice.
For example: Let's say, just for fun, that they do utilize a tobacco extract for their tobacco juices. And let's say that they use the same tobacco extract for three of the flavors. Now, if they pre-made 'x' amount of juice in each nic-strength, they could easily run out of someone's favorite juice/nic-strength, and be left with zero ingredients to make more.... because they're spent in the other pre-made juices. Make sense?
This can be alleviated by making each order fresh. By doing this, they'll save on scrapped ingredients as well. They open the store, orders come in, they tally up amounts of each juice/nic-strength that needs to be made, and make 'em.
It's not like they're mixing one 18ml bottle at a time, at least, I wouldn't imagine that to be the case.