Numbers in title are a good indicator that the article is 1. Opinion based and that it 2. Lags detail.
At least it's enough for me to know to avoid it when I'm searching for a solution to a problem.
This is one of those things I try to google every once in a while but the results are so clogged with junk that I still don't really know the answer. Why are our brains drawn to click on headlines/titles with a number?
I don't know exactly and I wasn't able to find a reference either but I thought the increase was something like 30%. Maybe hubspot or buffer has a blog on it.
It’s true. Odd numbers do better than even, as well.