One grid of every court and every hour. App bookings, walk-ins, phone bookings and league fixtures all land in the same place, so nothing is booked twice.
Platform and direct bookings are marked apart, so you always know where a booking came from.
A slot that is already taken is refused, and the details you typed are kept so you can pick another.
Block a court for maintenance and it disappears from the player app until it is back.