There has been substantial research exploring the capacity for parallel processing of multiple tasks. Recent studies revealed that some individuals prefer parallel processing while others favor a more serial processing style. To gain further insight into whether individual multitasking strategies reflect traits or states, we investigated their dependence on task environment predictability using the task switching with preview paradigm (TSWP). In classical TSWP, two tasks are displayed and alternate in a fixed sequence (e.g., every three trials). The stimulus of the currently irrelevant task (preview) does not change so that its response can be prepared. Previous applications of TSWP revealed that some individuals process the preview in parallel (overlapping processing) to optimize their switch performance, whereas others opted for serial processing. We extended TSWP by introducing blocks with variable task sequences, where tasks alternated unpredictably every second to fourth trial. Given that the upcoming switch was unpredictable in variable sequence blocks, we expected a reduced use of the stimulus preview by individuals preferring overlapping processing in blocks with variable relative to predictable task sequence. Preliminary analyses of currently 40 out of 60 data sets indicate performance reduction in variable relative to fixed sequence blocks, especially for overlapping processors. While this results in a shift to more serial processing under conditions of reduced predictability, individuals with an overlapping processing strategy in fixed sequence blocks still outperformed serial processors in variable sequence blocks. The results’ implications for the underlying mechanisms of overlapping processing and the ongoing state-trait debate will be discussed.