Psychology says people who focus on one thing at a time aren't less productive: What this behavior may reveal?

Psychology says people who focus on one thing at a time aren't losing time by avoiding multitasking. Cognitive science shows that the brain switches attention between tasks instead of handling them at the same time. Single-tasking can reduce mental fatigue, lower errors and support memory. The behavior is linked to limited working memory, attention switch costs and the need to manage distractions.