Exactly because they are new, they don’t need to complicate things by different pg/vg. You have one premixed 20/80 bottle and your average mix will be somewhere in between 30/70 and 40/60 (and the difference between these two even someone who is vaping 10 years wouldn’t know for a new recipe; not saying for your hundred times exploited recipe, but for a new recipe).
This makes everything simpler for a new mixer; dealing with one bottle instead of this scientific approach that just confuses them to get exactly 30/70 (which is least important at the end and neither they or most long time users would not recognize the difference). Making it simple(r) is important for newbies.
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For bottles… nearly every newbie has this wrong expectation and they mix too much (by quantity) instead of just enough or too little. Because mixing small quantities makes testing and finding best vapes possible, not mixing 120ml bottles. Because too many times you will end up with throwing away 115ml of liquid or be forced to vape that mediocre mix, which obviously doesn’t happen with smaller bottles. I would recommend getting big bottles only after a year or two, when you already have your adv or preferred mix that you already had dozen of times.
easier to work with smaller bottles
easier to adapt recipes to your liking (or add additional flavors to recipes you already know / to experiment / to get know the difference)
easier testing (testing 5 different variations instead of just one with the same amount of ingredients used)
allows you better vapes in average (it’s easier to throw it away if not optimal since only micro amount is used or to eventually ‘correct’ recipe afterwards; thus one can vape more pleasant juice than he could otherwise)
allows you try way more recipes (with the same amount of ingredients)
It makes sense. Just like it makes sense to not make 100 glasses of home-made marmalade when you’re doing it first time or 100L of home-made liqueur / moonshine when you start with that.
Yes, i do believe it’s wrong to say a newbie that he needs 10x 60ml AND 10x 120ml bottles when making first ever order.