One customer per ticket type
Dedicate one entire ticket type for a customer at a time.
This is great for time slot events, where you have private sessions for each time slot. A good application is Lane booking for bowling.
Create 6 ticket types, called Lane 1, Lane 2,.. Lane 6 and activate this feature on each one.
When a customer purchases any amount of tickets for a particular lane, the rest become unavailable for other customers to purchase - meaning no strangers can crash their bowling party.
To activate this feature on your tickets, look for the setting below under "Advanced Settings" when creating or editing your ticket type.