Cleaning here is done by the hygienist rather than squeezed onto the end of a dentist's appointment, and she works three sessions a week in chair four.
That is why the booking form shows so few hours for a scale and clean. It is not hiding availability; those are the hours. They fill about two weeks out and reception keeps a list for cancellations.
She will also tell you plainly how you are brushing and what to change, which is the part of the appointment that actually does something between visits.