I have to wait 20 minutes in between each question I ask on Stack Overflow. If I had more reputation would this period be lessened or removed?
To answer your question directly, I was able to submit two questions within two minutes, so apparently the rate limit on asking questions is reduced/removed at some point. (Possibly when you're elected moderator.)
However, as indicated in the comments, it really does take some time to craft a quality question that can be reasonably answered. (I had to tinker around the quality filter to get two questions in so fast.) Twenty minutes is a reasonable time to wait.