The part nobody models: the 20-minute reset. Every room has to be rebuilt between groups, so one booking occupies 80 minutes of calendar, not 60. Booking 19:00 blocks the room until 20:20 and the next offered slot is 20:30 โ never 20:00. Blocked windows stay visible, labelled IN PLAY and RESET IN PROGRESS with diagonal hatching, so the customer understands the constraint instead of hitting an invisible wall. This is the exact mistake Mariana made every Friday, booking back-to-back from chat and then running.