Workflow systems have been widely recognised as a successful way of modelling business processes. The issue of workflow optimisation has received a lot of attention in the literature, but the issue of temporal constraints in this area has received significantly less. At the same time, issues that come from the enterprise, such as actors performing tasks, resources that these tasks utilise, etc. have not been taken into account. This paper proposes a combination of utilisation of enterprise modelling issues and temporal constraints in order to produce a set of rules that aid workflow optimisation and therefore, business process improvement.