Much easier to have a quicker count when you only have one or two races on a ballot. He also does not care how our elections work. The reason some races are known earlier is that the winner can be projected earlier as one is further ahead. In those cases, ballots are still being counted but no change is expected. When it is close, you don't know until every ballot is done.
Oh yeah, I suspected many places had same-day and paper ballots during the Truman/Dewey election.