Although composing has long been recognised as recursive, so far there have been few studies on the temporal dimension of writing processes. This is regrettable given that one might expect the predominance of certain processes at different stages of writing at the expense of others and/or differences among writers with respect to the duration and distribution of the processes throughout the composing act. To shed light on these issues, we report on a study in which we (i) used protocol data to investigate whether the writer's proficiency level influences the total processing time devoted to writing processes and (ii) compared the differential distribution of the time allocated by different proficiency groups to different writing processes at each stage by dividing the writing session into three different stages. Two main findings emerged from the data: (i) formulation took up the largest percentage of composition time for all groups and (ii) writing processes are differentially distributed across the three periods depending on the writer's proficiency level. These findings are discussed with respect to their relevance for model building and suggestions for future research are advanced.