Vegetables can release a lot of water. The amount and how much it affects the other ingredients varies significantly on which you put in, in what order, how much, and in what size of pan. If the pan is crowded, has high walls, or a lid, that can also affect how much water stays in the pan.
I can't think of any situation where I would want more than a literal tablespoon of oil for cooking the first veggies thrown in (usually onion). By the time the onions have begun to caramelize there's is enough water that the original tablespoon of oil is no longer significant.
I can't think of any situation where I would want more than a literal tablespoon of oil for cooking the first veggies thrown in (usually onion). By the time the onions have begun to caramelize there's is enough water that the original tablespoon of oil is no longer significant.