Model planning is an umbrella term that encompasses two types of planning.

Business Planning is directed at improving the performance of each company-owned model. The effort is model-specific: if more than one model is owned, a unique strategy is developed for each.
Strategic Planning is directed at designing the portfolio of models. It's the process of determining which models belong in the enterprise and which do not. Strategic planning strives to create an enterprise that is synergistic, i.e., one where its constituent models interact to balance out the weaknesses of the other(s).
"Planning" is, perhaps surprisingly, a concept that divides the academic and practitioner worlds. Whatever they call it, most executives use at least some form of whole-enterprise planning. Academics, on the other hand, strongly resist all linkages between their academic domain and planning. If you're curious, Henry Mintzberg's The Rise and Fall of Strategic Planning is a fascinating, accessible read. Henry was one of my professors; his influence upon me is now "bred in the bone."
To learn more about the different types of business model planning: Chickens and Pigs - The Book