PERT Chart is an important project planning and management tool. Unlike Gantt chart, it provides task dependencies with earliest/latest start/finish dates. It also shows the "critical path" which shows that the delay of any of the tasks on that path results in the delay of the overall project.

Since many projects only utilize Gantt, when you have a look at the project plans, the dependencies of tasks, deliverables and milestones are only realized during the execution of the projects. PERT chart, on the other hand, provides a visual overview of tasks and their dependencies and enables project proposal developers to have logically connected tasks, deliverables and milestones.

However, it is not as often used as Gantt. One of the reasons is that creating PERT chart is more difficult than Gantt chart.

There are a number of tools that help create PERT chart graphically. However, when project schedules change, updating the charts is cumbersome as it requires recalculating the values of start/finish dates for the remaining tasks and identifying the critical path.

In order to address this, pertchart [1] -- a python library -- developed to generate pert chart from text file containing tasks, their duration and dependencies. It also helps to automatically adjust the whole network and the critical path in cases where changes are made on the work plan. All the user has to do is change the tasks that are affected. The rest of the network is automatically adjusted. Give it a try and let me know your experiences with using it.

Do you know any other reason why PERT is not used as often as Gantt?

[1] https://pypi.org/project/pertchart/