One of the most common questions asked of Project Managers is: “How many of your projects were completed on time?” Responses to this question often vary based on individual perspectives and organizational context. In my view, if we strictly consider the original timeline agreed upon at contract signing, the percentage of projects completed exactly on schedule should not exceed 10% for most Project Managers—particularly in environments that follow a waterfall delivery model.

There are numerous reasons why projects experience delays. I have explored several of these factors in my article “What if a Project Ends on Time?” Additionally, challenges related to freezing scope during the bidding phase are discussed in “The Competitive Bidding.”

In most cases, project delays cannot be attributed solely to the Project Manager or the delivery team. More often, delays result from a combination of factors. A common issue is unclear or incomplete scope definition at the start of the project, which only becomes fully detailed during execution. Agile methodologies acknowledge this reality through the concept of progressive elaboration, which helps keep stakeholder expectations realistic as the project evolves.

Scope changes are another frequent cause of schedule slippage. As deliverables are reviewed by customers, new ideas, enhancements, and requirements naturally emerge. In some cases, scope changes are introduced deliberately to support business strategies or gain competitive advantage. Technical challenges, often referred to as technical spikes, also contribute to delays, as unforeseen complexities arise during execution and require additional time to resolve.

Delays are further compounded by dependencies on customers or third parties. Assumptions made during project initiation, such as the timely availability of resources, licenses, integrations, or external inputs do not always hold true. These dependencies are largely beyond the Project Manager’s control and can be particularly frustrating due to the uncertainty around their resolution timelines.

Another common source of delay is the time taken by customers to provide approvals or formal sign-offs. Departments such as Information Security often operate under their own standard operating procedures and work queues, which may not align with project schedules. These delays are rarely intentional but are a consequence of internal priorities and governance structures.

Ultimately, regardless of the reasons behind schedule overruns, the conversation often circles back to the question: “How many of your projects were completed on time?” While delays are common and often unavoidable, the reality remains that the original timeline was missed.

A more meaningful and outcome-focused question would be: “How many of your projects were completed successfully?” By success, I refer to projects that were formally closed through appropriate documentation, ceremonies, or defined processes. When viewed through this lens, the percentage of positive outcomes is significantly higher and far more representative of a Project Manager’s true effectiveness.