Traditional research emphasizes the costs of multitasking; however, recent work highlights robust individual differences in how people organize multiple tasks, shaped by their preferred processing modes and response strategies. Using the Task-Switching-with-Preview (TSWP) paradigm, we identified whether individuals preferred an overlapping (parallel) or serial processing mode. In TSWP, participants complete three trials of Task A (or B) while previewing the upcoming stimulus for Task B (or A) before switching tasks. Some individuals use this preview to prepare and switch rapidly (parallel mode), whereas others complete tasks sequentially without using preview information (serial mode). Response strategies were probed using the Free-Concurrent-Dual-Tasking (FCDT) paradigm, where both tasks are also presented concurrently but participants freely choose when to switch. Individuals typically adopt either a blocking (>10 task repetitions) or interleaving strategy (frequent switching). To examine how these preferences unfold across the adult lifespan, we compared younger (N = 72) and older adults (N = 70) in an online sample. Given age-related declines in working memory, executive control and divided attention, we anticipated a higher prevalence of serial processing in the TSWP and blocking strategies in the FCDT among older adults. If preferences remain stable with age, older adults who prefer overlapping or interleaving were expected to show an age-related decline in multitasking efficiency. Our findings indicate adaptation at the level of processing modes but stability at the level of response strategies: older adults showed significantly more serial processing, whereas strategy distributions were comparable across age groups, though older adults were less efficient.