Family schedules — work, school, activities, appointments, social — accumulate mental load disproportionately on one parent (usually mother). Visible shared calendar removes the mental cataloguing burden and surfaces conflicts before they become problems.
What works
Shared digital calendar (Google Calendar, Apple Family). Every family event added by either parent. Color-coded by family member. Visible from all family devices. Big printed monthly version on fridge for quick view.
What stops working
One parent maintains everything (just shifts the mental load). Calendar only on one phone. Important events still relayed verbally between parents.
Two weeks to establish the habit. Most users find the cognitive relief of not having to mentally hold all family scheduling is substantial.