Well let's look at a timeline:
December 07 - Patch Y
June 08 - Patch Z
August 08 - Scirocco spotted/announced
December 08 - Scirocco stated for release
September 09 - Rockingham spotted/announced
October 09 - Patch Z25
November 09 - Patch Z28
Clearly it takes time to put together the Scirocco (early 08) and Rockingham (scanned in early 09 it seems from the addition of the big corner names which appeared on the tyre barriers and the V1 stuff) - we can only hope that in the time since the last piece of slight content (a lot) more has been produced...