Our dentist has moved us onto annual check-ups as we're allegedly low risk patients. He claims it's Scottish gubbinsment requirement.
The guidance changed in 2004.
https://www.nice.org.uk/guidance/cg19/chapter/Recommendations It meant dentists could agree with the patient a variance from 6/12 examinations as appropriate, and it was supposed to depend on need.
Any changes to the recommendations inevitably have unintended consequences. A practitioner local to me put everyone on annual exams regardless of how much decay they customarily devoloped and this lead to cavities being detected much later than they otherwise might have been. Another continued to recommend 3/12 checks with the hygienist, regardless of the health of their gums, leading to even greater profits.
Me, I judged it just right, of course