Sophie Leroy may have an answer. In her paper, she coins a term called “attention residue,” which accounts for multitasking’s inefficiency. She explains that when people switch tasks before finishing the current one, they continue thinking about the incomplete task subconsciously. This is akin to exiting an application without closing it on your computer (which drains the battery).
She also found that rushing people through an activity reduces attention residue and increases perceived competence on the task. This might explain the efficacy of process-oriented goals; by measuring success based on time allocation (i.e. achieving a goal of reading 10 minutes today) our brains can fully devote itself to the next activity.
Although thinking about something subconsciously (also called rumination) boosts creativity, it’s important to know when to cut your losses and work on the next goal. I hope this idea expands your cognitive toolkit.