Can't you learn a foreign language really well within a few months?

You've done some well thought out ysis of the situation. Here is why your idea, good though it looks on the surface, will not work. If a loaf of bread cooks for 30 minutes at 350 degrees, can't I cook it just as effectively by putting it in the oven for six minutes at 1,750 degrees? Naturally, this won't work. Certain processes, like baking bread or absorbing the structure of a new language, must take place over time. Your idea that there is a minimum amount of exposure which has to happen in order to achieve success is correct, however. Linguists think it takes about one thousand hours of instruction, and additional hours of homework and practice, to bring an adult to a "conversant" ability in a new language. And there are other factors to consider. But you are wise to think about things in the way you do. Apply that same reasoning to the handling of money, and watch yourself grow rich.