Isn't it about the 'head' word? If run, wall, team, etc are treated as singular, then the adjectival forms for them - 4 mile, 12 foot, 5 woman, will simply agree with this singular.

While we may not see the particular 'logic' in this, it appears to be a consistent rule. Even when the head noun is pluralised, we seem to remember this rule - "There were 12 five-foot walls around the courtyard".

cheer

the sunshine warrior