Think it depends what you mean by demanding FT rolls. DH and I run our own company, have 2 x DC 15 months apart, and live no where near any family. DH parents have had our kids who are now 9+10 once overnight and they live an hour away. My MD and DF are amazing but live 4 hours away, so when kids were too little to go to nannys house for a week over half term, it was tough.
I imagine if you were doctors, solicitors, FDs of a FTSE 100 it would be impossible. But we are alway busy and always work FT. Difference is, no one is "in charge" of me and I dont have to answer to any one.
We work from home and DC primary school is 300m from my house. DD was ill yesterday at school and I got a call to collect. 5 minutes later I had her with me and she spent the afternoon in my bed in the house or on my sofa in my office.
So it can work, but I think you either have to pay for childcare / nanny / aupair or work for yourself. And ultimately my DH and I have the same attitude that we all pull together and if its a choice between work or kid, our kids always win.
When they were really little we would pick them up from childminder at 3.30 pm and when we had put them to bed, we would go back to work in our office with the baby monitor until 10/11 pm at night sometimes.
We also have thins like phone answering service company, who deal with all our calls, text us emergencies, etc so even if we are cooking kids breakfast we can still deal with an emergency. So being really organised helps no end.