As for me, I can't put a number on it, really.
I'm not a person who needs to see my lover constantly. I don't like to place an arbitrary time constraint, or obligatory time, upon my lover.
Perhaps she could be really busy with something, or needs some alone time, so I might not see my lover for the whole week.
However, if something tragic happen to her, or she needed my company, I might go the whole nine yards, and see her for the entire week, including sleeping with her.
Vice versa for her. Maybe I might need some alone time, or I'll need her constant presence. I don't see the latter happening, actually. I like to be alone when I'm having problems.
In light of the above, it's difficult for me to figure out an average. I put 24 hours a week, or about 4-5 hours a day.