Route planning helps you to plan lots of repeated task in a way that minimizes driving.
F.ex. you may have 100 tasks that are planned for an employee in next week, in no particular order, and you want find an efficient way of assigning the tasks to each, to minimize the time spent driving, then you can use the Directions module to suggest the route. This is available in the Planning module, in PLANNING > Route planning.
Troubleshooting Route Planning