As I said earlier, this is a ridiculous argument because obviously people fill the time they have. If you have 3 hours in the evening, you will think you "do it all." If you have 5 hours in the day, you will just do a few more things.
If you are a SAHM and, like me, have a few DC at school, you would be surprised how much if your day is taken up doing random stuff related to them. For instance, yesterday, by the time I got back from the school run, DD called me in a panic to say she had left her homework, so I took that over to her (20 mins drive there and 20 mins back). On the way back, I went into M&S to get the girls new underwear and tights. Then I needed to take one of their violins to be re-strung. It's the other DDs birthday tomorrow so I went to get the party bag stuff for 25 girls and all the other stuff for the party, before I picked up DH's suits and did a good shop. So none of it earth-shattering stuff worthy of special mention no, but I'm still rushing about nonetheless.
Obviously, If I was at work, this stuff would probably get done, but just less of it.
I'm never bored and never have been. Most of the time I feel there aren't enough hours in the day! I have 4 DC in 3 different schools and a DH who is quite full- on. As I said earlier, the school holidays when I have all 4 DC at home feel less rushed than the school weeks.
No I don't feel guilty in the slightest about "doing nothing" in the day. I had 10 years of having at least one school-aged child with me at all times. I can't tell you how much I value my own space these days. I don't sit down between 4 and 11pm because I literally do everything in this house and I'm up at 5.30 every day, so if I want to take a few hours to recharge during school hours, I will.
Yes I can go for a run and do "me" things in the day. My DH is more than happy for me to do stuff for myself. He encourages it. He is not hard done by - he's off in a car-racing holiday next week and I don't begrudge him doing his sports and trips away.
So basically, the whole debate about "doing it all" is like asking how long is a piece of string.