Just want to throw the Herd Winter Racing example out here for discussion:
Single, 0-1000 ZRS category. Usually have a strong front of field and a wide variety of rider strengths. (Front group of 12 on Sand & Sequoias with ZRS between 826 & 602)
None of the ZRS stuff looks crazy based on first glance. The ZR.app time cut seems BRUTALLY aggressive for this type of race.
https://www.zwift.com/ca/events/view/4547263/5750038/1#results