If we are to have more women at the top of politics or business, we have to have, as a starting point, fewer of these women who want to go pt indefinitely and spend time 'jogging at the bottom'.
Sure, not everyone wants to shoot for the moon, but those that do are overwhelmingly male. Until women show that burning hunger to get to the top, why should organisations turn themselves inside out to accomodate half hearted ambivalent candidates.
Then on top of that, there are the changes that the organisation must make to remove the hard and soft barriers that stand in women's way, like stop writing employees off who want to go pt or downscale for a short period of their lives, more mentoring for women and grooming them for top posts, and being aware of attitudes how they are reacting to women (e.g. women seen as aggressive but men seen as assertive, women having less presence, no or small network for entertaining).
These attitudes take a long time to change, but it is not helped if so many women just want to be the supportive act at home rather than an equal if not more powerful force in the workplace.