beamur and scotchmeg...on the 'me time' thing..and i am just speculating here, so forgive me please if I am entirely off-base here. But I think it seems to work out differently in some step cases and that is why it is not so straightforward.
With a fulltime residential situation, sure, teenagers of 16 or 17 are there all the time and so there is a shortage of 'me' time, or 'we' time! But ideally, life goes on...because the kids are old enough to look after themselves, the couple can go out. Because the kids are old enough to have independent social lives, they will be going out sometimes. And because the kids are capable of entertaining themselves, even when everyone is in the home together, the need for constant attention is much less.
Ideally! But I have heard of a bunch of cases in which it seems like the 'natural' progression into teenage life has been kinda stalled....teenagers who come for their stays with the DisneyDad who then stops normal family life and turns cruise director...turning 'family' life into a parade of entertainments for the teens. In these cases, it seems like the days when the teen is at the home, instead of being a household with teens living in it, the household becomes something else, with the other residents taking a backseat to the teens for the entire duration of the stay.
In the cases where things are normalised...where teens split life between two homes and both sets of parents carry on with routine life...this seems to work as it should. But a problem arises when teens in a divorce are given special status in one home, by a parent who is afraid of alienating them or boring them or arguing with them...or basically, treating them like they would be treated if they TRULY were just 'at home' in either household.