In Maintenance > Misc. 3 there is a “use large appointment slots” check box.

If this is unticked, then the space per appointment slot is smaller to keep a whole clinic on one page without the need to scroll to get to the later appointments.

If the box is ticked the appointment slots are larger but you do need to scroll down to see what appointments are available later in the day.

For example, in the below screenshots, Both clinics have 30-minute intervals but the clinic on the left has the box ticked so the slots are larger, and you must scroll to see the later part of the clinic. The clinic on the right has the box unticked so the slots are smaller and the whole day can be viewed at once.