The other thing to note of oil, albeit many fluids exhibit this; it can look really bad, or not at all. I don't specifically look to cars, but if you see a good pool of fluid, most oils will spread over an engine, the surrounding panels and can coat quite quickly, although they're not actually going through much oil at all. I leaked through a quart an hour on a 180hp engine, some time ago...want to talk about a lot of oil everywhere...that was a mess, extremely notable.
Even if you see quite a mess (mentioning 1 qt every 1000 km/miles) may not be as such. Lots of great advice above on what actually happens; however the crux being, trying to find the leak can be a real pain when it really does go everywhere, especially as airflow can push it around and gravity helps it can essentially get everywhere. Only by cleaning the workplace, i.e. the engine and oil lines, can you probably start to take a stab at finding the source to fix that leak.