Why the last 20% of a project is the hardest

Most people have heard of the 80/20 rule, also known as the Pareto principle. Named after Italian economist, Wilfredo Pareto, and popularized in the “80/20” book by Richard Koch, it states that 80% of effects come from 20% of causes. Its premise is to focus only on doing the few things that give you 80% of results.

Unfortunately this idea doesn’t perfectly align with project management. Do you know what an 80% complete project is? A failure. 

Imagine if a paint contractor came over to your house, painted all your walls in each room, but never took off the tape, the trim, or touched up any missed spots. Would you consider that project complete? Heck no.

An 80/20 rule does exist for project management, but it’s slightly different. On a successful project, the last 20% is the hardest to finish. Why is that, you wonder? It’s all because of the S curve of completion. 

The S curve, which looks like a horizontal S shape, shows that the beginning and end of projects have slower progress, while the middle section experiences rapid progress. 

In the beginning of the project, the slower start is understandable because people are just getting familiar with the scope and team. Once they ramp up, they make successive improvements and progress speeds up. 

Why is it then that progress slows down for the last 20% of a project? Why is the last 20% so challenging? Here are four reasons why:

Progress isn’t as visible

There’s a certain excitement in seeing progress manifest. When you’re painting a room, for instance, and you see the color change — it makes you feel great. Doing the last 20% of activities that don’t move the needle much, like adding additional coats, or painting that tiny piece of trim, is where you might start to lose steam. This lack of motivation could extend to your team on a project — even a super successful one, making the last 20% to completion extra challenging.  

The work is more tedious

Usually the work involved in the last 20% of any project is more tedious. To illustrate, let’s use an everyday life example — like moving. You would think the bulk of the struggle would be done once you’ve moved all the large pieces of furniture like the sofa, the bed, the dining room table, but no. It’s all the little stuff you’re carrying from the moving truck into the house that makes the last 20% all the more challenging: safely transporting fragile heirlooms, carrying large paintings, the T.V. — you get the idea. 

People leave

As a project reaches the home stretch, people tend to either leave or at least start looking for their next big adventure, which can greatly reduce productivity and slow progress. 

But it makes sense. Let’s say you were working on a hot new car for Tesla. The exciting part is designing it and building it, right? The last 20% of the project—putting the finishing touches on HVAC ducts, touching up paint, and making sure things aren’t broken—this is less interesting. If you’re a showman, the whole show already happened, so you look for the excitement of a new project elsewhere. 

While there are some personalities that thrive on detail-oriented assignments, most enjoy the excitement of a project’s early phases more. 

The hard work is sometimes left for last

Some tasks on a project are inevitably left for last — but this doesn’t mean they’re easier to do or unimportant. It’s just that they are less urgent on the list of priorities, and now that you’re in the last 20% of your project, it’s time to deal with them, sometimes all at once. These punch list activities can be stressful and make the final portion of your project extra challenging. 

An example of a task that would be left for the final stages of a project would be reconciliation. Let’s say you spent the last two years building a skyscraper and it’s perfect in every way: sound engineering, immaculate wiring, beautifully designed, elevators and escalators are all in working order. But now you’re transferring everything over to your client and they need to have perfect records of everything you worked on in that building, because for the next 100 years, they will own and operate it. You’re not just the builder of the project, you are the record keeper and the majority of documentation-heavy tasks are saved for the home stretch, making the project’s final stages more challenging. 

So do you think the last 20% of a project is the hardest? Why or why not? Tell me in the comments below or @theomarproject on Twitter.