Planning, Schedule, Execution: Implications

In our last post we considered Execution in the context of Planning and Scheduling; now, let’s summarize our findings and consider why and how we uniquely consider these domains.

To accomplish an objective we plan: we break our objective down into a series of steps we can follow to achieve it efficiently. We include sufficient detail to reasonably ensuring feasibility, more detail in earlier steps. We measure how well our plan meets our objective, how well we’re following our plan, and re-plan remaining steps as circumstances change. The better we plan, the more likely we’ll succeed.

We schedule when efficient task sequences aren’t obvious. Finding an optimal schedule is likely impractical, so we often use specialized logic and tools to help us out, looking for good answers fast. “A bad schedule from a good plan is better than a great schedule from a bad plan.” (S. Sidhu, i2)

We plan/schedule to help us execute: to do the right things at the right times in the right ways to efficiently achieve our objective. We freeze the portion of our plan/schedule required to preserve prep time and leave it out of our re-planning/scheduling workflow, managing reality real-time during execution.

For several key reasons, we consider these three domains separately and uniquely.

1. The objective in each domain is unique, so the tools and logic employed in each should suit the relevant objective.
2. The horizon in each domain is unique: Planning considers the entire unfrozen horizon; Scheduling considers an initial, smaller unfrozen horizon within the plan; Execution considers the frozen period.
3. The measure of success in each domain is unique: Planning considers the final objective(s); Scheduling considers localized efficiencies within the plan context, and Execution considers work quality and conformance to the plan/schedule.
4. The detail required in each domain is unique: Planning has just enough detail to reasonably ensure high level, overall plan feasibility; Scheduling requires significantly more detail to ensure efficiency and executability; Execution must manage to all of reality in real time.

Planning, Scheduling and Execution: considering planning theory and recognizing similarities, differences, and interdependencies helps us position the proper skill sets, logic, tools, workflows and data within each domain, and to integrate them effectively to ensure success.