I think the reason women say they need big blocks of time to get work done in is not that they do not know how to work efficiently. As I keep saying, anyone who got a PhD and a job does know how to work efficiently.
Where the front time goes, the first half of the four hour block of which only the last two will really be used for work, is to thinking oneself back into the identity of the person that does that work.
Because if in the rest of life, including professional life, that identity is being attacked, undermined and eroded, the first thing one must do to get work done is to put oneself back together, remember who one is or was.
That is why it is important to remain in that identity at all times, not become the one that is being projected into you, even if survival, in the moment, seems to depend upon not resisting the projection.