A process model is a visual picture of business activities.
Since a picture is worth a thousand words, a lot more information about a business process can be communicated with a process model rather than just words.
When creating a process model keep in mind that it is a communication method. What specifically about the process is trying to be communicated through the model.
Models can be simple models or they can be rigor models. Rigor models have strict notation such as BPMN (Business Process Modeling Notation)
If the exactness of a modeling notation helps communicate your intent, then they are invaluable.
If your intent is simply an overall understanding of the process then BPMN does not add value, just takes more of your time.