Great discussion and one I had just today with someone new at work..
Cessna hit it on the head when he said consistency is key.
I have been making mixes for some years now and while I don't claim my eliquids are the best, there is one thing you need to realize when mixing you're recipes, consistency.. I know some go by drops, some go by ml and some by weight.
I have never gone by weight, but if you do, and the recipe is great. Keep it that way. Now let's say you go by weight,and you do a 10ml but just happen to see a flavor in your arsenal that may add that something to make it better, and your scale isn't around so you add say 5 drops. After a week or so, ( you did date the label and the recipe on the bottle of course)
And you find that it is awesome. Better than you thought it could be, but you added those 5 drops which you didn't weigh. What to do???
You make that recipe the same way every time. You weigh the original ingredients and when done you add 5 drops to top it off . It doesn't matter if it is 10 ml, 30ml, 120 ml. This is consistency and will give you the same result every time.
I use ml myself or percentage in my calculator, but I also use drops sometimes.
So let's say I have to make 500ml of a base flavor, but at some point along the way while working on the original recipe in a 10ml bottle I happened to add 2 drops to that bottle. Of something that made it spectacular, well, when I make that 500 ml amount. When I get done adding all the Ml's of however many flavors it has, I then sit there and I add 100 drops of whatever that additive was I added. And I do it that way every time.could I add the drops to a ml syringe and see how many drops make a ml and then just multiply by that? Sure. But I assure you that it would not be the exact same recipe I liked before. It would be close, but I don't want precision I want consistency in my recipe bases , minus nicotine of course.
Once in awhile you can get away with using a syringe when using drops. But you would, or at least should, make a test batch first.
Whatever way you do your recipe. The thing to remember is to ALWAYS make it the same way, this way you have consistency. And while the statement. "You don't always have to be precise, you just have to be consistent" seems to go against my above example. It doesn't