The first question likely to be asked, is why start a discussion about project management with the project lifecycle? The answer is simple; the lifecycle is the roadmap for the project, the definition of the project delivery process. The lifecycle is the means by which the project will be controlled.
It doesn't matter which form of project management style you subscribe to, agile, scrum, traditional, etc., there is still a need to define the project lifecycle. Too simple a lifecycle model won't give good control and too complex a lifecycle model and the project can be stifled with 'red tape'.
Another word of caution here; the lifecycle model is NOT the project plan, as it has no dates directly associated with it. To convert the model in to the plan requires the addition of those dates and those are very project specific, rather than being a model of the project delivery process.
For organisations with large or complex projects they may find that they need different "project managers" at different stages of the project lifecycle. This is because projects evolve with different levels of uncertainty and different management styles and tools are needed as projects evolve. On smaller projects this requires the project manager to be flexible and evolve his style as the project progresses.
World Class project lifecycles (or processes) have 'stage-gates', which allow high levels of churn within the stages, but retain overall control by ensuring the project continues towards its business objectives at each gate. Cutting edge project management systems allow modular elements of the design follow concurrent sub-processes ultimately being integrated in to the overall project.
The best project lifecycles also emphasise business aims. Early opportunity analysis is an essential part of project lifecycles. This ensures the focus is on "doing the right project, NOT just doing the project right".
None of this alleviates the need for a good project plan. That, however, requires tools at the right time and is a separate but related discussion. The time and cost plans (schedules and budgets) need be developed based on the level of uncertainty indicated by the project lifecycle.
Some concern has been raised during a discussion that Planning is setting out the project philosophies and anything else that moves you closer to the project end is Doing. However, this is too simple a view on Planning and Doing and is why we explained this in greater detail in one of our white papers or this external site [Max Wideman].
Most sectors have a step that can be described as Design. Thus, Design is about moving towards the completion but also about Planning the detailed execution.
As with many things, we advise caution with simplified models like the Plan-Do lifecycle. Contact us to arrange training in Project Management