I think it depends on your goals. If MidWest U is the place you want to be, then put all your effort into it and go for it. There is little point in applying to a place you know you don't want to be. You just need to be prepared for what might happen when you put all of your eggs in one basket. If they don't let you in, are you prepared to work for another year? Will you try to re-apply to the same place or completely revisit your goals?
If, on the other hand, you KNOW you MUST get an MBA this year, then you've simply limited your options for doing so.
It's all about you, your goals, and your priorities. I would also add that the risk you take depends a bit on your likelihood of getitng into a given school. If you're an average candidate who doesn't stand out, then applying only to one ultra-elite school is probably a rather futile exercise. If your aspirations are more realistic, applying to only one program isn't such a risk.
And don't let these 10-school applicants freak you out. It's about what's best for you.