We are a family of 6 soon to be 7. DH is the laundry person in our home and he does all the laundry on Sundays - usually three loads (dark, light, whites) - sometimes two loads of darks. If we have a baby I do diapers about every other day on my own. We do sheets/towels every couple of weeks on Friday or Saturday.
I want to edit to add that the three bigger kids fold all their own laundry, and DH has taught them to sort it, too. They also fold the 2yo's things. DH folds his and my laundry. I don't fold diapers :p I do fold sheets but the kids fold their own blankets and the towels.