In this study we examine process configurations in synthesis tasks. We study whether these configurations are students traits or vary within students per task. In a national survey with a representative sample of 658 Dutch upper-secondary school students, we collected writing tasks, registered students' writing behaviors (via keylogging) and their task perceptions and assessed the quality of their texts. Each participant completed two informative and two argumentative synthesis tasks. Writing process configurations were based on a preselected set of writing behaviors that proved to be related to text quality: time spent on sources and production activities, switching between sources and between sources and text production, and speed of production; with reference to the phase in the process (first, mid, final part). Latent profile analyses distilled four process configurations, some of which were more likely to occur with the informative genre. One process configuration, that is, "Fast text production," was related to qualitatively higher text quality scores than the others. Additionally, at the age of 16-18 a writing process configuration is not a student trait: in most instances, we observed two or more task configurations within students. Writers' task experiences such as topic knowledge and topic interest predicted the occurrence of certain process configurations which could indicate adaptivity. The finding that writing configurations of writers vary even between similar tasks has important implications for the generalizability of (synthesis) writing research on the basis of a single writing task and process per student.