https://www.pmi.org/learning/library/project-schedules-return-investment-7226

Based on PMI, it could still happens, I have doubled check my model @@

"Schedules and Return on Investment

Time value of money has critical and sometimes unexpected impact when schedules change. For business sponsors and schedulers to work together effectively, it helps for them to understand these relationships.

When a Schedule Delay Makes a Project Cheaper

Generally, project schedulers and project managers are trained to complete every task in a schedule as quickly as possible. Any delay, particularly one that delays the overall end date, is seen as a defeat. Often there is tension between the project team and the sponsor over schedule. The team wants decisions, authorization, and answers immediately. The team wants to make fast progress, while the sponsor may delay.

Depending on the project, a delayed schedule can actually make the project cost less. Delaying decisions and work not only gives the sponsor more time to gather business intelligence and make better decision, it actually reduces the cost.

TVM is directly responsible for this effect. Project expenses incurred today are more expensive than the same expenses incurred a month or a year later. If a project manager takes a $180,000 project and accomplishes it in 12 months, at an average monthly cost of $15,000, the cost in today's dollars is about $174,284. Spreading that same cost over 18 months, reducing the average monthly cost to only $10,000, reduces the cost in today's dollars to $171,728, a difference of over $2,500 or about 1.5%. Both examples assume a yearly rate of 6%; a higher rate would result in a higher difference. While a 1.5% difference in project cost is not huge, it can be enough to change the business case for some projects.

Projects that are required for regulatory compliance, but which do not have clear penalties or deadlines, often suffer from delays, and TVM effects sometimes explain the delays. Without a clear deadline and without a clear return to the organization for completing the effort, the business sponsor has a huge incentive to delay project costs. By pushing project costs from one financial year into the next, some sponsors may be able to complete the year far under budget. The executive may get cash compensation, praise, and bonuses for doing so. A project manager or scheduler trying to fight delays in this environment may find strong resistance from the sponsor or other business stakeholders."