"Is it necessary to report clear of Class D airspace when exiting the area?" - Tom C.
“No, there is no requirement to report clear of the Class D airspace when exiting, except when requested by the Tower.
Occasionally the Tower will request this report if traffic is a factor or you are on a special VFR clearance.
It’s important to recognize that a pilot is required to maintain two-way communications with the Tower while in the Class D airspace. Therefore, it is important to know the boundaries of a particular Class D.
Generally, the Class D is constructed using a four nautical mile radius around a towered airport and extends up to 2500 feet AGL. However, a given Class D might be tailored to accommodate specific instrument approaches.
Details on the configuration of a specific Class D airspace can be found on sectional charts.”