It seems their approach, and this is used by other successful nations like the Italians and the USA and GB women's squads, is to minimise changeovers as these slow the team down. Two riders do long stints, the lead off rider who does 3 laps, and the final stint rider who does 4 laps.
Just been reading the following article over on cyclingtips on the Danish team pursuit squad, and the comments below are really interesting.
https://cyclingtips.com/2020/02/denmark-smashes-mens-team-pursuit-world-record-for-third-time-in-two-days/
It seems their approach, and this is used by other successful nations like the Italians and the USA and GB women's squads, is to minimise changeovers as these slow the team down. Two riders do long stints, the lead off rider who does 3 laps, and the final stint rider who does 4 laps.