With me it's closer to 1-8 hours a WEEK. Sometimes I'll go a few weeks without doing anything at all in my sewing room.
I am: a business owner, separate full time job, wife, home owner, gardener (1/2 acre of beds + greenhouse), breeder/exhibitor of Champion dogs, writer (regular columnist), and lecturer (4-6 x per year).
I also have a hard time sitting still - high energy type (which is the reason my ironing board is on the opposite end of the room from my sewing machine!). I have to be busy.
8 hours of sewing in the same week would be a LOT for me. If I have a deadline though, I'll put in whatever hours it takes to finish it on time.