$1 by EOY, page-20

The way you elaborate and track a delivery plan is by creating a list of task, associate workloads based on experience, add resources, define dependencies and a critical path, and finish by adding some contingency on top to cope with unforeseen delays.

The numbers shared with us are just the tracking of that plan as they work through the different items, they are indicative in nature but nonetheless correlated to progress of the different activities