Lists + a half-hour-early buffer

RCT (n=38) of a multimodal intervention combining time-processing training and 'time-assistive devices' — including weekly/step-by-step schedules, written reminders, alarms and graphical timers — improved daily time management and time-processing ability vs an educational-only control. Directly supports externalizing scheduling/lists as a compensatory scaffold, though in children and as a package, not the isolated 'arrive 30 min early' tactic.

Meta-analysis (~20 RCTs) of CBT for adult ADHD, whose core content is exactly these compensatory skills — time management, scheduling/planners, to-do lists, organization — found medium-to-large symptom reductions vs waitlist and small effects vs active controls, plus improved functional impairment and quality of life. Lists + scheduling are validated as components of an effective package, not in isolation.

RCT (n=88) of metacognitive therapy built around time-management and organizational skills (calendars, task lists, planning) showed significantly greater improvement in inattention symptoms than supportive therapy — supporting the working-memory-offloading rationale behind list-making.