As mentioned above, checking and comparing different alternatives is essential for optimal planning, and APS systems are irreplaceable in this respect. The What-If functionality, or scenario analysis, utilizes and combines different algorithms to generate alternative scenarios that take various factors into account.
What makes this option so useful (and practical) is the system’s speed. For example, in discrete manufacturing encompassing several plants and a total of 35,000 orders, resulting in 80,000 operations and requiring the consideration of 20,000 components, APS can generate subsequent schedules every 10 minutes.
This example illustrates a very complex situation. For typical planning tasks, time to generate schedules is usually a few to a dozen seconds (e.g., 3 seconds for 300 orders, 600 operations, and 40 000 components). To achieve a similar performance, you only need workstation-class computers with quad-core CPU running at 4GHz or higher and 16-32 GB of RAM, depending on the complexity of the model.
Of course, the mentioned speed parameters depend on the algorithms and models implemented in the specific system. It is also important to consider not only the speed of an APS system but also the optimization efficiency, as it’s not difficult to calculate something quickly but inaccurately. Nevertheless, almost any APS system will be far more effective at supporting scenario analysis than a spreadsheet.