Whether your sister-in-law should clean for you is entirely a matter of circumstance and opinion. There is no general answer.
a cow
We should keep our home clean.
You should make sure that its in a clean place but you should clean it every few days
you should clean it once a week
You should clean the screen and the casing.
You should clean it everyday that you use it.
You should clean it every day.
You should clean your Clarinet every time you play in it.
Listerine should make it sterile and should clean the site
Clean the dishes.
You should clean a water bucket in a stable one a day
you should clean your years at least twice a day