Purpose - Aims to describe a successful use of simulated knowledge worker behaviour used in the developing online procedures and software for arbitration - the E-Arbitration-T project Design/methodology/approach - Presents four common factors - deadline, length of task, importance of customer, importance to business - that need to be incorporated within any business process model of knowledge worker behaviour. Findings - A richer model of knowledge worker behaviour is postulated and elements not necessary for the E-Arbitration-T model are identified. The knowledge worker's day was defined as being made up of Scheduled, On-demand and At-will tasks, only some of which may relate to the business process being modelled. A particular question that must be addressed in this extended model is how to model the choices knowledge workers make between competing at-will tasks. Originality/value - The two pieces of work reported here have generated a rich model of knowledge worker behaviour ready for application and refinement in further business process modelling studies. © Emerald Group Publishing Limited.