As Jaycia tells the story now, Justen wasn't exactly sure what he thought of Sterling until...the puzzle was opened. That is when Justen discovered how intensely focused Sterling can be. Sterling worked on the puzzle from the time it was opened until it was finished. People would be getting dinner and Sterling would be working on the puzzle. People would be sitting around visiting and Sterling would still be working on the puzzle. I assume you can see the pattern and this is how "Christmas time is puzzle time" came to be.
This year proved Justen right. We got three puzzles for Christmas and Sterling and mom finished two of the three while the family was out here visiting. I never stayed up long enough to witness their obsession but Joseph did tell me that on at least one occasion (although it was probably more) Sterling and mom stayed up until 2:00 am working on one of the puzzles.