It says within ten years. That is to say, no more than ten years. In such manner pretty well covers the content of the census. It could be every year, or every day. They could not only ask, but count for themsleves, how many frozen fishsticks are in your freezer.
Where do you get that?
"and within every subsequent Term of ten Years"
Which means every ten years, depending upon the time congress established the original census rules. It never says, do it when ever you feel like it. You're reading way too much into this simple statement. Just like everything else that has been bastardized by politicians, this is no different. The constitution is pretty simple, there isn't a right to abortion, there is no seperation of church and state, etc, etc, etc. It says ten years.