2nd alarm to a 'highrise' is a large response...
Think if the primary response is 205 31 201 203 204 to a report of Commercial Fire, not only are you having to backfill those trucks with COQ, however then when the 2nd alarm was struck,you are sending a 2nd alarm compliment, still having to fill adelaide, fill the stations that went on 2nd alarm, fill the stations covering those stns, etc etc... Hence why CFS are required..
The 2nd Alarm upgrade to any confirmed response is going to pull in alot of resources, particualry CBD and being highrise.