In general, you should source every statement you make about a person. Now, if you say your grandfather loved to fish, that doesn't need to be sourced but if you say your ancestor served in the Revolutionary War, that would need a source. When working on some profiles that have been disputed, I add every fact and source I can find. Some of those have around 50 citations.
Is every census needed? If the person stayed in the same location and you don't need the census to prove children or things like birthdate or state of birth, then you may not want to add it.