Sincere question to SAHM's who have all school age children

Hi hard working SAHM's. No rude comments please!
 I was sincerely interested in picking your brain. When all your children are off in school for 6-7 hrs a day what do you do in the mean time? 
SAHMs don't need to do the rat race but I was trying to add up the hours during school time and affordable after care for that age. I'm still confused why some or most? SAHMs don't go back to work? Not that one has to but why stay at home?
   Us parents know that there's housework, bills, cooking, exercising, volunteering time at school, etc happens But What do you do with the remaining time?