One of the most common mistakes I see in CRM is the decision to use a checkbox as opposed to a completed activity.
A checkbox is easy to add and easy for a user to "click on", but it totally bypasses the ability for the system to track historical information. It is also a feature that is harder to audit trail as the checking of or the unchecking of a checkbox is not easy to track. (although with creative workflow it is possible)
So if you are thinking about "adding a few fields" to increase the communication from your teams and people around what has and has not been done than you might want to think a bit more about the whole picture.