One would hope so.
Doing this on an ad hoc basis, looking at one individual building type at a time, creating an administrative infrastructure, different designation processes, and different criteria for different purposes--all of that is very expensive, and all of that leads to gaps in terms of conserving other equally important types of heritage resources.
I think the other thing to consider is that if you look at Canada's historic places in a comprehensive fashion, you would have to be very cognizant of the federal interest, and you would have to make sure that designation criteria really dealt with the most important representative examples of our cultural resources. I think that's probably the benefit of a comprehensive approach. It immediately gets you into that frame of mind.