I'm not sure exactly how many times I have to remind myself to chase down every single available census entry for every person in my database. I found another missing one. Specifically, I had missed the 1930 entry for Alfred John Chasse and his wife (my relative) Sarah Jane (Anderson) Chasse.
When I checked the 1930 census, I had too many entries under Alfred or Sarah Chasse; however, when I looked for their daughter Janet, the family popped right up. The only reason I knew about Janet was because she appears with her parents in a 1941 city directory. Janet was born 31 Dec 1920, which was after the 1920 census was taken.
In 1930, the Chasse family is living in Biddeford, Maine and they have a son. John Anderson Chasse (b. 4 May 1924 Biddeford, York County, Maine) is fairly easy to trace; however, as a researcher, I had to know he existed to look for him! Thus we have me learning yet again to pay attention to census entries and to make myself systematically track down every last one of 'em.