MrsDeVere - I think that is a really important point, there are loads of different ways of working that people choose for all sorts of reasons. There shouldn't be any judging really as no one knows why someone is doing what they are doing.
In my job I had to go back 4 days a week. It was that or nothing. 4 days a week pays for school fees and the mortgage etc but it's not as simple as some who say 'cut back'/ 'don't pay school fees/don't have expensive holidays' and then you could be a SAHM - without my money we couldn't afford the mortgage or bills let alone the extras.
I'm not sure I've explained that properly but say I earnt £70k, if we 'cut back' I'd 'only' need to earn say £20k for bills/mortgage, but in my career you can't do less hours so I'd have to resign completely to be a SAHM, therefore earning £0 which means we'd lose our house.
In short - everyone does what they think is best and for their own reasons and I hope it works out for them 