You've read all three installments of the Strategic Gamemastering posts, and you're telling yourself that while the method certainly could work for one-shot scenarios with strongly divergent characters, you are still in doubt that the THACOSG tool could manage the several pre-written adventures, modules or 50-scenario campaign that you have bought for your favorite game.
Your main issue is that if, in accordance to the process described in Part 3 of Strategic Gamemastering, you decompose a single scenario into its base components and enter them into the THACOSG for subsequent exploitation, the player-characters will enter the scenario in a manner certainly consistent with their own objectives or background, but probably not in the manner envisioned by the scenario author but by each following their own creative agendas.
Since player-characters will be entering the narrative threads of the scenario in an uncontrollable and unpredictable manner, there is also a definite possibility that the scenario will unfold in a manner wildly different from the author-driven narrative direction. This, of course, implies a massive uncertainty as to whether the ending of the scenario will match the beginning of the next campaign scenario as envisioned by the campaign designers !
These reservations are quite legitimate. However, the Strategic Gamemastering method also provides for long-winded campaigns and even follow-up campaigns. This post will show you how.