Often there is the requirement, that data imports should be automated if possible.
We could not find a possibility to import holidays into the holiday scheduling for usage in the SLAs.
I understand that it does not seem to be possible to programmatically import holidays (calendars/calendarrules internal use limitation). But there is an excel import functionality, which does not work either - I get the message "The 'Create' method does not support entities of type 'holidaywrapper'. MessageProcessorCache returned MessageProcessor.Empty." for every holiday.
So maybe it would make sense to at least support Data Import / Excel Import to create the holidays in bulk.