8-10 hours but that really depends on the day (whether DD has school, the weather as DH is self employed and works outside, whether I'm working at home) but on an average day when everyone is gone it's roughly 7:30-4.
There is only one day a week they are left alone if even, each Friday my parents go out, so depending when i'm finished work myself, but my brother does be at home 9 times out of 10 with them anyway so maybe 2/3 hours every month is all.
10 hrs a day, during the very hot summer days and the very cold winter days.
There is about a two month window in the spring, and a two month window in the fall where the weather is cool but mild enough that I can bring them to work - they stay in the car in their crates, but they get breaks and a lunch hour walk, and extra time to run and play in local parks and fields after work before I start the home commute.
But they do very well when they do have to stay home - no issues, except for an over-excited Gryffie when I get home - but that's not really a complaint.
I leave for work at 7:30 and come home for lunch at 12:15, leave again at 12:45 and home by 5:30. So I guess the longest would be near five hours during the week. On weekends only as long as it takes to go grocery shopping every two weeks. Otherwise, the weekends are ours. I do not go out at night during the week unless I have to. Hate leaving him while I am work. If I did not have to, would stay home and play with him all day! LOL