> The four-minute barrier was first broken on 6 May 1954 at Oxford University's Iffley Road Track, by British athlete Roger Bannister
> On 21 June 1954, at an international meet at Turku, Finland, Australia's John Landy became the second man, after Bannister, to achieve a sub-four-minute mile.
In 1955 Laszlo Tabori was the third person to break the 4 minute barrier. Then, in 1956, three runners broke the four-minute barrier in a single race.
This matches what I described, multiple people attained it once it was understood to be possible. It was linear up to the 4 minute mark, but the point is that records that used to be impossible are now humdrum once achieved.
With for example: "What this shows us is that the issue wasn’t massively psychological. If it was, we would have seen athletes running 1,500m races much faster than their corresponding mile time. Instead, we see that the progression matches up nicely. People were stuck on 4 minutes at the same time they were stuck on 3:43. Do we really think that runners were stuck on a mythical 3:43.0 barrier?"
In case you don't want to read it, it says that other distances had similar "breakthroughs" but they were not associated with a mental barrier like "4 minute mile". Rather, the article argues, the development may have been related to WW2.
Edit: it just so happened that for mile running, the stagnation after WW2 occured just around the four minute mark. You need to look at other distances and perhaps even other sports to see the pattern.
Indeed, my country Sweden won the olympic football/soccer in 1948 - a result widely regarded as being due to other countries have sent all their young men to the war while Sweden stayed neutral/did not fight the germans.
> The four-minute barrier was first broken on 6 May 1954 at Oxford University's Iffley Road Track, by British athlete Roger Bannister
> On 21 June 1954, at an international meet at Turku, Finland, Australia's John Landy became the second man, after Bannister, to achieve a sub-four-minute mile.
In 1955 Laszlo Tabori was the third person to break the 4 minute barrier. Then, in 1956, three runners broke the four-minute barrier in a single race.
This matches what I described, multiple people attained it once it was understood to be possible. It was linear up to the 4 minute mark, but the point is that records that used to be impossible are now humdrum once achieved.