Cappytan has it the way I see it. The Watchtower of 2010 with the "overlap" is still the official doctrine that explains why everything from "1914" to "this generation" to "soon" to even how Adam was 6000 years old in 1975 is CORRECT, but it is so ridiculous that they want to leave it in place and not mention it anymore. Plus, they print stuff for years, even decades, that is so vague and then they later point to their own printings and say "See, we've been leaning this way for a long time."
For a little while after the 1995 change in "generation," I fell for that for awhile. I would see how they would point to their own words from recent past study articles as if that was the word of God and we are just catching up on it.