You can view your Appointedd calendar in the interval increments which you find most appropriate for your business:
Go to the Setup tab and click Customize business settings
Click the Calendar interval increments you wish from the dropdown
Please note that this will affect the time slots at which you are bookable. For example, if your interval increments are set to 30 minutes, you can only be booked at half past an on the hour.
You can further customize at which interval increments you can be booked on your online booking tools in the online booking section of the settings. For example, you could view your calendar in 30-minute intervals but only allow customers to book on the hour online.