While any adult children living at home should take on some responsibility, I wouldn't use 'laundry' as a measurement for that.
It is energy/resource efficient to combine laundry loads. It would be a waste to separate out 1/3rd for a separate run, unless the washer was already full.
As long as she is aggressively seeking a job, and looking for at least part time work if that becomes an extended task, I would not charge rent. How would she pay it w/o a job? If she decides to stay at home once she lands a job, rent is a consideration, but it could be considered a gift, to help her get started in life. As long as she isn't being 'lazy', I don't see a problem.
I'm still curious about this being a 'shock' - from my earlier post:
Hmmm, is the OP still around? I don't see any responses?
-ERD50