Projects are often planned at a summary level and then at a later date detailed out before the work commences. Smaller projects may be scheduled in detail during project planning, but large or complex projects may require several iterations before the project plan is fully detailed out.
The main reasons for not detailing out a project early are that:
- There may not be enough information at that stage and
- Preparing detailed schedules wastes time, as they may be made redundant by unforeseen changes.
The following planning techniques discussed in other well-known project management books may be considered:
- The Rolling Wave. This technique involves adding more detail to the schedule as the work approaches. This is often possible, as more information is known about the scope of the project as work is executed. The initial planning could be completed at a high level in the Work Breakdown Structure(WBS). As the work approaches, the planning may be completed at a WBS Component and then to a Work Package level planning.
- The use of Sub-projects. These are useful in larger projects where more than one entity is working on the project schedule. This situation may exist when portions of projects are contracted out. A sub-project may be detailed out when the work is awarded to a contractor.
- The use of Phases. A Phase is different from a PRINCE2 Stage, as Phases may overlap in time and Stages do not. Phases may be defined, for example, as Design, Procure and Install. These Phases may overlap, as Procurement may commence before Design is complete. The Phase development of a schedule involves the detailing out of all the associated WBS elements prior to the commencement of that Phase.
- The PMBOK® Guide does not have strict definitions for levels of plans but assumes that this process is undertaken when decomposing the Work Breakdown Structure (WBS). There are some other models available that may be used as guidelines, such as the PMI “Practice Standard for Work Breakdown Structures.”