I do (for 2 adults and 2 dcs aged 3 & 6)
1 x white wash -school polo shirts, white bottom sheets off boys beds, vests, sports socks
1 x black wash -dh's work trousers, underwear, socks, t-shirts
1 x light colours - work shirts, my clothes, duvet and pillowcase from 3 yr olds bed
1 x dark wash -mainly boys stuff, reds, dark blues, duvet cover and pillowcase from 6yr olds bed
1 x tea towels, dishcloths, flat mop heads
1 x bedding wash - ours
1 x towel wash
so about 7 washes a week, always full loads as my machine doesn't do a half load.
I try to get it all done in the week as I am a sahm so that weekends are washing free
I have a 6kg capacity drum.