Even if my analysis is slightly incorrect (slightly incorrect would mean F K races 800m high 1:56.xx). No matter, Faith Kipyegon isn't ever going to race low 1:55 800m like you gals/guys are stating.
Lasse Viren & M Farah could race final 600m in (84 to 86) second range, 5000m & 10000m. Neither were capable of racing 600m much faster. Same for Eamonn Coghlan and his final 600m, 1983 World Championship 5000m final. Give E Coghlan two or three days rest, mid-70s to mid-80's. Eamonn wouldn't have been able to run fresh much faster, 600m.
Do you believe John Walker was a secret 1:42 800m man? By your logic, after splitting 800m, 2:03.xx, Rick Wholhuter and Ivo van Damme should have raced for gold & silver, 1976 Olympics, 1500m final.