In reality, it's easier. I peruse a lot of soap recipes online and when they don't provide percentages, you're obligated to make the size of recipe they made (i.e. 5 lbs of oils or 1 lb of oils). You can't simply halve or double a recipe; you need to run it through a soap calc first, to make sure you don't have too much or too little lye (and that's just for sizing). When it's written with percentages, you can, along with a
soap calculator, size the recipe to whatever size YOU want to make. I've found some interesting recipes that I've changed to percentages for my own use.