Bastille are another act where our measure deserves a clear caveat. The English band, led by Dan Smith, have had a genuinely successful career since the early 2010s, with multiple hit singles, chart-topping albums, and a string of high-profile collaborations. Few people would instinctively call them a one-hit wonder.
But "Pompeii", their breakthrough from 2012, operates on a different scale to everything else they have done. Its chanted hook and surging chorus made it a global smash, and on streaming it sits past 2 billion plays.
The rest of the catalogue is real and substantial, with songs like "Good Grief" and "Things We Lost in the Fire" pulling hundreds of millions of streams between them. Even so, dividing the hit by their second biggest track gives a ratio of about 5.17, just over our 5.0 line.
So by our strict, numbers-only measure, Bastille register as a certified one-hit wonder, narrowly. We flag it as the borderline case it is: an active, multi-hit band whose defining song has simply pulled far enough ahead to tip the maths, and whose verdict could easily shift with their next release.