Why Do So Many Projects Succeed on Paper but Fail in Reality?

There's a lot to unpack with this question. You're talking about three different kinds of failure - strategy/initiation, execution/delivery, and outcomes. It's easy to blame the project, but if project execution/delivery was successful, but the product or service was not, the failure was either strategy/initiation or outcomes, both of which are often outside the purview of project managers. There are things a project manager may be able to do overcome a strategy/initiation failure or reduce the likelihood or impact of an outcomes failure, but I'm working on staying on topic in my responses.

When it comes down to it, I don't define true project success. I don't want to understate the amount of hard work that goes into some projects, or the sense of accomplishment at the end of a challenging project, but I think it would be more appropriate to think of it as effective delivery, not project success. Projects deliver the potential to produce value, in the future, using a new/updated product or service. Calling it "effective delivery" alludes to cost, scope, schedule, and quality. Actual value, as opposed to potential or planned value, comes from successful utilization of the delivered product or service.

Delivering the product or service is effectively "preparation". More accurately, it's just part of preparation. There should also be a plan for how to use what is delivered, monitor it's use, and possibly make sure it's achieving ROI within a reasonable timeframe. This is something a project manager can help with. I've managed projects where I had to remind people to do this, and I've managed projects where the business owner did this and did not involve me in it. It's our job to raise awareness of the need for a benefits/value realization plan, but not always our job to deliver it.

Project dynamics have changed a lot, lately.
Traditional KPIs still matter, but they alone are not enough anymore.
Real success is about business outcomes, value delivered and actual impact, not just outputs conforming to the iron triangle.

There's a lot to unpack with this question. You're talking about three different kinds of failure - strategy/initiation, execution/delivery, and outcomes. It's easy to blame the project, but if project execution/delivery was successful, but the product or service was not, the failure was either strategy/initiation or outcomes, both of which are often outside the purview of project managers. There are things a project manager may be able to do overcome a strategy/initiation failure or reduce the likelihood or impact of an outcomes failure, but I'm working on staying on topic in my responses.

When it comes down to it, I don't define true project success. I don't want to understate the amount of hard work that goes into some projects, or the sense of accomplishment at the end of a challenging project, but I think it would be more appropriate to think of it as effective delivery, not project success. Projects deliver the potential to produce value, in the future, using a new/updated product or service. Calling it "effective delivery" alludes to cost, scope, schedule, and quality. Actual value, as opposed to potential or planned value, comes from successful utilization of the delivered product or service.

Delivering the product or service is effectively "preparation". More accurately, it's just part of preparation. There should also be a plan for how to use what is delivered, monitor it's use, and possibly make sure it's achieving ROI within a reasonable timeframe. This is something a project manager can help with. I've managed projects where I had to remind people to do this, and I've managed projects where the business owner did this and did not involve me in it. It's our job to raise awareness of the need for a benefits/value realization plan, but not always our job to deliver it.

Love the question and the answers! Taking away the effective delivery and the monitoring of the impact and added value after delivery. Thanks!

Most projects don’t actually fail in execution.

They fail in translation.

We translate strategy into plans, plans into work, and work into outputs—but somewhere along the way, we lose the original intent.

A project can hit every traditional KPI—on time, on scope, on budget—and still fail because the problem it solved wasn’t the right one, the assumptions changed, the organization wasn’t ready to absorb it, or no one was accountable for what happens after delivery.

So I don’t think the issue is that traditional KPIs are wrong. They’re just incomplete. They measure delivery efficiency, not whether the underlying decision was the right one or whether it actually led to impact.

In my experience, real success comes down to a few simple questions:

Did we make the right decision in the first place?
Did the organization actually change behavior as a result?
And did it produce measurable impact over time?

Projects don’t create value. They create the conditions for value. The value only shows up when what’s delivered is actually used—and too often, that part gets treated as someone else’s responsibility.

If we want fewer “successful failures,” we have to stop treating delivery as the finish line. It’s really just the handoff.