They idea is to have a Prince/Princess of a segment as a contender for the crown of KOM/QOM.
This status can be achieved during the calendar year, and will be reset each year.
The reasoning behind this is multiple
Fresh year, fresh achievements
KOM/QOM are unreachable for the 'normal human'. KOM/QOM by pro cyclists for example
On mountain bike segments, times can change during the year due to trail conditions
maybe more use cases are possible
Practically the period of achieving this is each year beginning at 1 jan 00:00 local time of the start of the segment and ends at 31/dec 23:59. So yes this means each year the first rider on that segment receives this achievement, but on popular segments this will quickly go to the fastest rider of that year.