Many people go get an annual physical. Going only when you feel sick will not show your overall health and the changes in your body. It is not needed to go to the doctor's twice a year unless you are immunocompromised, once a year will suffice.
Explanation: Michael isn't planning this with time in mind. Because they don't know who has which task that is why it is always. A good idea to plan something out Earley so your group knows what they're doing.