Point of hourglass?

What’s the point of the hourglass? I always thought, until I googled it, that boil for one, two or three turns meant - boil, let it stop, boil, let it stop and so on. When I googled it people said that two turns and so on meant two turns with the hourglass. Yet, with my method, I have never failed a potion so far.

It’s just used as a measurement of time. If you mix all the ingredients as close as possible to the recipe you can get 3 potions for the price of one (without perks). If you mess up somewhat you’ll get less. If you really mess up, you’ll get an unknown potion, that does nothing as far as I can tell.

Um… I guess the sandglass is just an interest element which is not necessary.