In pastry making, it's another matter, if you need 250 gr of flour to make a shortbread dough for example, you'd better put 250 gr and not 270 or 230, because at best the dough will become a bit too soft or a bit too hard. This is what makes the rigor that is imposed on pastry cooks, and that without a scale, and it is understandable, they are (a little) lost ...
When you weigh powders or liquids like that, no worries, you just have to be careful, but sometimes with "indivisible" ingredients, it's a bit more complicated.
You can find recipes that indicate, for example, very precisely, "Add 85 gr of egg".
Well obviously it's different from "add 2 eggs", what to do?
Should we ignore it?Knowing that 1 egg is about 50 gr => 2 are about 100 gr, so a "medium" error let's say. Let's be clear, if you make a 4/4 it won't change much, but if you make
choux pastry (for example) it's not the same thing, you might have a too liquid pastry, sticky and difficult to form with the bag.
How to do it then?Well, here's the trick: break enough eggs to have more in weight than you need (use a container with high sides), then give a blow of
mixer in the eggs, 3 seconds are enough.
Then pour the exact weight you need into your recipe preparation container, 80g for example. The rest of the eggs can either be kept in the fridge for 1 or 2 days, frozen, or used in another recipe.
Please note that professionals do not use whole eggs anymore, for speed and hygiene reasons, because it is always delicate in a laboratory to break shell eggs by hand, the risk of salmonella is high. Instead they use what they call egg products, which are cans of pasteurized and mixed eggs, or yolks, or whites only. This packaging does not prejudge the quality, as for shell eggs, there are egg products made from battery eggs, cheap unfortunately, and others much better, up to organic quality.
To sum up: If you need to weigh eggs accurately, mix them and weigh what you need.