When More Planning Stops Paying Off
FEATURED PAPER
By Ricardo Viana Vargas, PhD
Lisbon, Portugal
and
Carlos Augusto Freitas, MSc
Brazil
Abstract
How much effort should a project put into planning? Too little planning causes rework, while too much planning consumes effort that the project never gets back. This paper proposes a simple quantitative model to find that balance. It starts from a break-even rule: additional planning effort G pays for itself when G ≤ R × P, where R is the share of effort lost to rework under minimal planning and P is the share of that rework the planning avoids. The rule is a valid test for a given plan, but it cannot locate the best amount of planning because it assumes that every hour of planning is as useful as the first one. We therefore add diminishing returns, P(G) = Pmax(1 − e−kG), and derive the optimal planning effort G*, the upper limit Gmax and a simple bound: when planning and rework hours cost the same, the optimal additional effort never exceeds R × Pmax / e, about 37% of the preventable rework. We apply the model to two illustrative cases, a software development project and an electrical substation, using deterministic calculations, a sensitivity analysis and a Monte Carlo simulation with 10,000 iterations. In both cases the optimum lies between 7% and 10% of the baseline effort and saves between 7% and 11% of the baseline labour cost, while planning above 22% to 25% destroys value. The optimum depends mostly on the size of the rework and on the relative cost of planning and rework hours.
Keywords: project planning; planning effort; rework; cost-benefit analysis; diminishing returns; Monte Carlo simulation
- Introduction
Most project managers have heard that time spent planning is time saved later, an old idea that is mostly right. A project that starts without clear requirements, a realistic schedule or a view of its main risks tends to pay for it during execution, usually in the form of rework. The same managers have also seen the opposite problem, with plans that keep growing, approval cycles that delay the start and teams that spend weeks refining documents that will change as soon as the work begins. Both failures are expensive, and the question that remains open in practice is where one ends and the other begins.
Research supports both sides of this argument. Dvir, Raz and Shenhar (2003) studied more than 100 defence research and development projects and found that success was positively correlated with the investment in requirements definition and technical specifications, while it was insensitive to the level of formal management procedures. Serrador and Turner (2015), with data on 1,386 projects, found an inverted-U relationship between planning effort and project success: projects can spend too little time planning, and they can also spend too much. Boehm (2002) framed the same question for software as a balance between two risks, in which too little planning leaves gaps that cause losses later and too much planning simply loses time.
In our view, what practitioners still lack is a simple way to put numbers on this balance for their own projects, and this paper is an attempt to offer one. Its starting point is a break-even rule first drafted by the second author, G ≤ R × P, which we extend into a model that finds both the optimal planning effort and the point where planning starts to destroy value.
The objective of this paper is to present, discuss and apply that model. It is not the scope of this paper to prove that planning improves project results, since the literature reviewed in Section 2 already supports that view, nor to propose benchmark values of planning effort by industry. The two cases in Section 5 use illustrative parameters, chosen to be plausible, to show how the model works and how sensitive its answers are.
After a review of the literature on planning, rework and planning effort in Section 2, the model is presented in Section 3 and the method used to apply it in Section 4. Section 5 applies the model to a software project and to an electrical substation project, Section 6 discusses the results, their practical use and their limitations, and Section 7 concludes.
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How to cite this paper: Vargas, R. V. and Freitas, C. A. (2026). The Planning Break-Even Point: When More Planning Stops Paying Off; Featured Paper, PM World Journal, Vol. XV, Issue XI, November. Available online at https://pmworldjournal.com/wp-content/uploads/2026/11/pmwj170-Nov2026-Vargas-Freitas-The-Planning-Break-Even-Point.pdf
About the authors
Ricardo Viana Vargas, PhD
Lisbon, Portugal
Ricardo Viana Vargas is the founder and managing partner of Macrosolutions. He was the first Latin American to chair the Board of Directors of the Project Management Institute (PMI). He also served as Executive Director of the Brightline Initiative and as Director of the Infrastructure and Project Management Group at UNOPS, the United Nations Office for Project Services. He holds a PhD in Civil Engineering, a master’s degree in Industrial Engineering and a bachelor’s degree in Chemical Engineering. He is a PMI Fellow and an IBGC-certified board member, has written 16 books on project management, risk and crisis management, and has hosted the 5 Minutes Podcast since 2007. He is an Honorary Global Advisor to PM World. Ricardo lives in Lisbon, Portugal, and can be contacted at ricardo@ricardo-vargas.com.
Carlos Augusto Freitas, MSc
Brazil
Carlos Augusto Freitas is Executive Director of CAF Facilities Management (CAFFM) in Brazil. He holds a master’s degree in engineering from Universidade Federal Fluminense (UFF) and specializations in project management (PUC-Rio and UNIRIO), telecommunication networks (PUC-Rio) and distance higher education (Fundação Getulio Vargas). He holds the PMP and CAPM certifications from PMI, as well as PRINCE2 Practitioner and ITIL certifications. His career includes seven years at Xerox do Brasil, five years at Golden Cross and four years as a project management consultant at Accenture, where he worked on a PMO for the oil and gas sector. He has taught at FGV Online, IBMEC, HSM and INFNET. A volunteer at the PMI Rio de Janeiro Chapter since 2007, he is a past president of the chapter. He wrote the first Portuguese-language book on the CAPM certification (Brasport), took part in the ABNT committee for ISO 21500 and served on the translation committee for the fifth edition of the PMBOK Guide. Carlos can be contacted at carlos.freitas@caffm.com.br.
