When working from home you can set your own hours and do as much work as you want too or need to so you make the required amount of money to support you or your family.
However if you run an online store from home such as an ebay store then you should ship out as many orders as you can in a day.
Your customers will hate waiting too long for packages to be shipped to them so in that cause I would actually work 8 hours per day or even 10 hours per day if needed to get the orders and ship out the orders.
But if I were blogging for a living or doing online freelance work from home then I would work as much as needed to make the income I need and then if I decided to not work any more than a few hours in the day then I would not push myself to work longer than the few hours.
Some days I would probably work 8 hour days and other days I would work maybe 1 to 2 hours in the day.
That's the good thing about working from home because you can work as much as you want too or as little as you want too.
And also you can just leave work if you need to without having to ask your boss for permission to leave the job early.