I've noticed that songs that have the biggest longevity are usually so strong because their is no song that is subsequent to it, or if their is it flops or underperforms. Like for GME, it has been so strong because ROM didn't do well. Same for IGF (MMH was a smaller hit) and Dynamite (no song came after it, or if it did I never heard it). Katy seems to be immune to this theory though.
I wonder if SB will be a huge seller in turn for Fly flopping. I would be down with that.