Whatever works for you. I just wash all the laundry because if I'm already in the laundry room it's no trouble to start his laundry after I put mine in the dryer. Just gives him one less thing to do when he gets home. Only certain items of his that I do not touch, but pretty much now I know what/how he wants certain things washed and what's ok to be put in the dryer and what should hang dry.
To not wash his clothes to me is like seeing he left a dish in the sink when I go to wash mine and I just leave it sitting there.
Now that I think about it...this may be an upbringing/cultural thing because my mom is the same way.