If you want to improve a process, it is important to measure before you map.
Always use measures that relate to the purpose of the process from the customers’ point of view, and use time-series measures in capability charts.
The measures will tell you whether it is worth taking the next step, mapping the process.
Capability charts will show you how much variation there is in the process.
They will also help you see whether your later actions for improvement make any difference.