The problems with the census would be remedied if it took place every 5 years instead of ten. Every two and a half years would be even better. If would give us a better chance to stay on top of the numbers and account for everyone. The 10 year census is too flawed.
Census problems would not be less important if the census took place every five years instead of every ten years. There would still be reporting problems and accuracy problems no matter what the time frame of the census. Census problems would still maintain the same level of importance, we would just have the problems twice as often!
Unfortunately, there is little matter in whether the census takes place every year, 5 years, or every twenty years, there will always be those who do not trust the government and find the census to be an intrusive event. Additionally, there can be some bias in people who are selected to assist in surveying. Therefore, there will likely always be problems with the census.
While the census can never be perfect because of the huge scope of the project it generally is able to get the broad picture of demographics and population numbers in America pretty accurately, adding a extra year to it would maybe make it more organized but there still be numerous problems with data collection, so I don't see a real benefit off making it every five years instead of four.
I think that would actually multiply the problems we're having with the census. Not to mention that it would likely also double the expense. The census happens every ten years because, among other reasons, it's insanely expensive to count every single person in the United States. Keep it at once per decade, please.