> after the barrier has been broken, dozens followed suit.

I read an interesting article about that explaining that this wasn't really down to any kind of barriers but more having pacers and a better track (which is coincidentally about the previous 2h marathon attempt.)

https://sportsscientists.com/2014/12/2-hour-marathon-4-min-m...

That, plus having enough time for a generation of runners to blossom after WW2.

I often wonder in cases like that if those who followed suit were not so much emboldened as already nipping at the heels of the one who did it first.

To mix metaphor with reality, there was perhaps a pack speeding toward the finish line, and one crossed it first.

It's probably a mix of both. Surprisingly (to me), not many were able to break the sub 4min mile immediately after Bannister broke that record - Landy was the second to break the mark a month or so after but he was already working towards it. I read in the 20 year span after the record, only 300 runners were able to match the sub 4 feat.

For an interesting read + obit of Roger Bannister, who first broke the 4-minute barrier:

https://www.nytimes.com/2018/03/04/obituaries/roger-banniste...