Nice example of selective reporting...
The pad that took 17 days was not the primary pad used, but a secondary "emergency" pad (and attached taxiway) that was built "just in case" due to this being the F-35B's first OT use of Austere basing. The 17 days also included the time to remove 4 inches of reinforced concrete and to build the attached taxiway. It was also build to last longer than just this exercise.
To facilitate testing of the aircraft’s VTOL capabilities in an expeditionary environment, Marine Wing Support Squadron 374 constructed a 204 feet by 200 feet VTOL PAD at the Strategic Expeditionary Landing Field. In addition, the support squadron constructed a 150 feet by 96 feet taxiway to connect the landing zone to the main landing field and hangar.
“Because this is the first time the F-35B is out here on an expeditionary landing field we built the [VTOL] Pad in the event that there is an emergency so they have more than one option to get the aircraft on the deck,” said Royer.
According to Capt. Jonathan H. Royer, assistance operation officer, MWSS-374, the landing zone will serve for emergency purposes throughout the remainder of Steel Knight 16 but has the potential to be utilized in future training.
The task depended on the heavy equipment required, to remove four inches of concrete before any other work could be done on the site.
The pad was also instrumented (again, due to the fact that this was a OT test).
"The early bird gets the worm but the second mouse gets the cheese."