I think one problem is an overestimation of liberation in the 1920s. The reason the flappers etc. are so iconic is because they were radically different from most women at the time, there were probably more sexually liberated women after the second world war but it was no longer a novelty. In Britain certainly there is doubt as to whether or not WW1 actually changed the position of women in society. The traditional argument that more women in work covering for the men fighting overseas inspired them to demand more, and showed society that they could do more. Gail Braybon however argues that the women who got into work during WW1 were working class women (who no one really cared about), who mostly had informal jobs anyway. As a result she argues there wasn't really a change, and we've just decided there was since.