Recovery Gap
FEATURED PAPER
By Alex Lyaschenko, PMP, MMath
Sydney, Australia
Abstract
For decades, project scheduling has relied on Total Float (TF) as a core network-analysis metric -describing how long an activity can be delayed without affecting the project’s predicted completion date. Despite its apparent simplicity, TF remains one of the most misunderstood concepts in scheduling. Inconsistent definitions across software, standards, and guidelines have created ambiguity, particularly when TF appears as a negative value, contradicting its definition as a measure of allowable delay.
This paper introduces a complementary metric, Recovery Gap (RG), to clarify schedule interpretation by distinguishing forecast-driven and target-driven completion perspectives. While TF indicates how much delay is possible before impacting the forecast finish, RG quantifies deviation from specific target deadlines. A negative RG value expresses the amount of acceleration required to meet the target completion date.
Three derivative forms, Recovery Gap Start, Recovery Gap Finish, and Super Recovery Gap, provide a structured framework for evaluating how individual activities align with project objectives and deadlines. Using practical examples, including resource-optimisation cases, this paper demonstrates how reliance on a single metric can mislead project teams, and how combining TF, RG, and related analytical metrics produces more accurate insights and more effective schedule-optimisation strategies.
Total Float Definitions
A persistent misconception within network-analysis methods, including the Critical Path Method (CPM), is that TF can legitimately assume positive, zero, or negative values. Although definitions vary, most agree that TF represents the amount of time an activity may be delayed without affecting the project’s completion or committed target events.
Representative definitions include:
- Definition N1a: Time by which activity can be delayed or extended without affecting the total project duration or delay finish date. (Planning, Scheduling, Monitoring and Control, Association for Project Management, UK)
- Definition N1b: The amount of time that a schedule activity can be delayed or extended from its early start date without delaying the project finish date or violating a schedule constraint. (Practice Standard for Scheduling, 3rd edition, Project Management Institute, USA)
- Definition N1c: The amount of time an activity can be delayed or extended before delay affects the program’s finish date. (GAO Schedule Assessment Guide, GAO, USA)
- Definition N1d: The maximum number of work periods by which an activity can be delayed without delaying project completion or violating a target (milestone) finish date. (10s-90 Cost Engineering Terminology, AACE International)
- Definition N1e: The number of work periods the start or finish of an activity can be delayed without affecting the project finish date. Float is measured in hours, days, weeks, or months depending on the project’s planning unit, and can have negative, zero, or positive values. (10s-90 Cost Engineering Terminology, AACE International)
- Definition N1f: The amount of time a task can be delayed without delaying the finish date of the project. (10s-90 Cost Engineering Terminology, AACE International)
- Definition N1g: Is defined as the number of workdays an activity’s finish date can slip before impacting the program’s end date. (Planning & Scheduling Excellence Guide, National Defense Industrial Association, 4th edition)
- Definition N1h: The amount of time an activity may be delayed without extending the critical path. (Praxis Framework)
While seemingly straightforward, these definitions contain subtle ambiguities arising from the use of terms that carry multiple interpretations.
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To read entire paper, click here
How to cite this paper: Lyaschenko, A. (2026). Project Delivery Plan Optimisation Metrics: Recovery Gap; PM World Journal, Vol. XV, Issue I, January. Available online at https://pmworldjournal.com/wp-content/uploads/2026/01/pmwj160-Jan2026-Lyachenko-Recovery-Gap-featured-paper.pdf
About the Author
Alex Lyaschenko
Sydney, Australia
Alex Lyaschenko is a planning and delivery consultant with over 25 years of experience in project portfolio management across different industries and countries. He holds a Master’s degree in Mathematics from Odesa Mechnikov National University and began his career in the technology sector and was at the origins of project management in Ukraine. He worked at Ukraine’s first project management consulting firm, where he helped establish project delivery offices across different industries and trained future project consultants.
After relocating to Australia, Alex contributed to multiple portfolio and program offices, supporting organisations in defining their vision, enhancing project delivery practices, developing standards, implementing PPM tools, and upskilling teams.
Passionate about merging data with actionable strategies, Alex continues to shape the project management field by delivering insightful presentations and practical solutions that empower organisations to make data-driven decisions. As a speaker, Alex has presented at numerous project management conferences, contributed to the 8th edition of the PMBOK Guide, and had his articles featured in leading industry publications.
Alex can be contacted at alex.lyaschenko@saluteenterprises.com.au
