The schedule is defaulted to generate time slots based on the chosen service duration.
However you have the option to switch to "Time based" availability.
Time based availability allows you to choose a particular interval length and generate a schedule which offers your clients more options in terms of when they can book with you.
You can easily switch to "Time based" availability.
Simply go to your "Company Settings".
Then select the "Client View" tab.
And finally, underneath "Schedule Display", select the "Time based" option along with an associated interval.
Thats it! When any customer now goes to book with you they will see your schedule in with available time slots for your chosen time interval.