Thats user preference, when you create a recipe with your preferred Nic level and preferred PG/Vg ratio, check the “Set these base values as default” box and then all your future recipes will be where you want them, one shot shouldn’t be any different, it’s just all the flavors already combined…
I dont think youre understanding that the ELR calculator already does what you are creating a calculator to do so youd be best to just carry on with it if it works for you.
I’m not sure what you’re having problem with, the calculator will tell you how much of everything to mix a finished e-liquid, if you have your preferences saved…
Once you have your one shot made; which is just pure flavour and no Pg or VG added you then “create new recipe” and add your percentage of “one shot” to the “add flavour” box. You put your preferred Pg, VG and nicotine percentages into the top boxes, exactly same as when you create a recipe. Save it and it tells you amounts of everything to add.
Your very talented, creation your own calculator.