After a bit of experimentation have found I can get rid of most of the FSX airfield default buildings that appear in Lawrie's FS9 Addons installed in FSx....by setting the FSX Scenery Complexity setting in the Display Setting to NORMAL....and the AUTOGEN setting between V Dense and Ex Dense....and so far all the addons that I have installed are now devoid of most of those annoying FSX default buildings.....though I am aware that there may be some variances between each individual's PC configuration.
Palmerston North, Kerikeri and Westport were some of the worst for these "default buildings" and the attached screenshots show the results....
NZPN



NZKK


NZWS


Bob R
Cheers,