Our DD8's homeschool day takes 3-4 hours, mostly because she tends to expand certain topics for the day, based on her interests. DW plans a number of activities for DD to complete at a minimum for the day, and then follows DD's lead for where it goes beyond that.
Wednesday is "fun day." They do art and science projects, or field trips. DD loooooves Wednesdays.
On another note, it's probably worth making a distinction between homeschooling and just general conversation. For example, DW has punted social studies to me (she's an immigrant), and I'd spend about 1.5 - 2 hours a week with DD on the material that the state says she needs to know as a 3rd grader. That was our "homeschool" time. At other times, when DD would go look at her chart of US presidents, and start asking me random questions about them, that wasn't homeschooling, that was just us chatting. The distinction being, she didn't need to know any of that stuff about presidents just yet.
