When I'm cooking, the thing that usually has the most leftovers, is the sauce. Most recipes always assume too much. This isn't a problem if you're cooking for just a handful of people, but it is a bigger issue if you're cooking for 20 people or more.
So, how much sauce does one person normally use? I'd prefer an estimate in milliliters.
To be clear, I'm asking for regular sauce, not pasta sauce. Especially about creamy sauces (mushroom, peppercorn, ...) that you can put on steak, chicken breast etc.