Janik,
You're absolutely right, this time crunch thing is a problem for me, let alone for someone raising kids. (You have my deepest respect, believe me.) It was hard for me when my son was growing up, but nowadays it seems like parents have even less time to spare.
I can only agree with everyone else that you have to work with the time you've got. If you can only workout once a day, have you considered circuit training? Perhaps intermixed from day to day with interval training? Those are the two most time effective workouts I can think of.
My workout schedule is not written in blood either - many times I have to come up with a compromise. Also, everyone is right that diet plays a major role (I'm sure you already know this) not only for losing weight but for keeping energy up.
I just think it's a darn shame that we live in a society where a working mother has to cut into her sleep time, which she obviously really needs, in order to fit in exercise time, which she also needs!
All any of us can do is the best we can do! You are obviously quite dedicated to do as much as you can. Good luck with it,
Ruth