I don't know. Planning policies are for the most part extremely subjective and driven by political agenda/directives of the moment in time. What good is a policy that makes no economic sense to the property owners? Say, the City develops a policy for Macleod Trail corridor, which is a principal gateway to Calgary Downtown from the south. How useful would it be without real incentives to re-develop and how likely these incentives are to be approved by Council?
I have always been in favour of spot re-zoning based on the merits of each individual proposal. This is a never-ending game and trying to predict and direct how the thousands of pieces of the puzzle are going to be re-developed in time is a losing premise. If the City is keenly intended to re-develop an important area in a concerted and well-planned fashion, the only alternative is to buy the majority of properties out from their owners and get into development business through a development authority (i.e. East Village & CMLC). There are numerous good examples of this approach when a blighted area needs special and additional effort to overcome economic and perception obstacles.