I forgot that every comment on MN should come with a disclaimer that every child is different, the post generally refers to NT and healthy people, who make up the majority of the population...
But I'll bite. I have two children, one toddler and one primary-aged. One was a decent sleeper, one a nightmare when it came to sleep (waking up to every 30-60min a night). One is NT and one has mild autism. I have had severe PND both times after my pregnancies, which lasted for about a year each time. One has allergies, which contributed to constant feeding and a reluctance to be put down for the first 8 months of her life. I have done the SAHP thing as well as the working f/t for up to 14 hours a day.
So, with that in mind: being a SAHP was by far the easier job. I got up with my DH each morning, regardless of how the night went and made him and DC1 food for the day. I had a shower each morning, children awake or not. If they were awake, the baby (now toddler) just came into the bathroom with me and - shock, horror - had to wait until I was done. I then got the children ready and did the school run. Then it was baby/ toddler time. Nothing needs to wait until they are asleep; washing, cooking etc. got done when they were awake. If necessary, I wore baby. I did almost all household errands with them awake. I haven't ironed in years; I just hang my clothes properly.
I insisted on routines, sleep training the awful sleeper - gently, with little to no crying, but enough that by 8 months she was in her cot and by 12 months she started to sleep through.
I insisted on teaching both children routines and responsibilities.
Both children have always been expected to help in the household, from the age they could walk. Little, age-appropriate things like putting their toys back before bed or if there was too much mess, helping to wipe their tables etc. Jobs, which made my life easier in the long run.
I got plenty of breaks during the day - children don't need constant entertainment and they learn just fine on their own as well as being included in everyday tasks. Both - even the autistic child - are far ahead in their development, so something must have gone right.
Smug? Too right, I am. Far too many people on here who sacrifice their all in order to constantly entertain their kids, do something special with them etc. and forget that the over-involvement of parents in their children's lives is a recent development and that children are fine and learn just fine if left to their own (supervised) devices for some time. Far too many people on here who think children cannot help, or who do everthing themselves rather than taking the long view with children and then wonder why their lives are so hard and resent it all. That's why the 4 hours 'entertainment' are alien to me.
Seriously, do you actually 'play' with your kids for 4 hours? And then wonder why things don't get done? No child needs their parent's constant involvement for that long. Young children find food shopping, going to the doctor's, posting letters, hoovering etc. just as entertaining. Learning is just that and doesn't happen separately from life.
So yes, with that in mind, being a SAHP is the easy part and the little bit of housework really doesn't take all day.