When you have a large amount of fire in an open attic space that you most likely will not be able to extinguish and the building is separated by some type of fire wall. Be pro-active and make a cut on the non-fire side. In the top photo we had three-story hotel with 48 rooms on fire. The fire wall was 40 years old. The decision was made to cut on the non-fire side. This also allowed us to complete the cut in reasonable safe conditions. While making the cut we observed fire penetrating numerous breaches and the heat was so intense that you could not have your face over the vent hole with-out a mask on.
In the second photo, a some what of a trench cut was made to release serious heat build up from the two-story townhouse that was fully involved on-arrival. The fire never breached the fire wall. The heat did however conduct through the fire wall and was visible after the cuts were made. The trusses were not damaged during the cutting and resulting in the owner being able to rapidly fix and allow the exposure townhouse to be reoccupied within a week. Still a couple of years later this entire block of row houses/townhouses were demolished due to extensive drug activity.
So in the end, be open to non-traditional tactics that may be pro-active and not understood by all. I would rather a hole in the roof of my apartment that can be easily fixed, than heavy smoke conditions and/or fire extension from serious heat build up that was not released. Trusses require us to sometimes complete pre-mature vertical ventilation based on the likely hood of the future fire growth.