Of course not all the helpers are working that hard la....it really take times to understand their real personality. After 1-2 years, you will see (if you are lucky that to have that person for that long). After a while, they will find their way to work more "clever"...especially if you are working mom.
I don't think so ge....unless she wants you to fire her. But better you set up a time table for her and give clear rules and instructions, otherwise, they will become lazy gradually. With black and white and ask them to sign to acknowledge what you have set and expect.