To help with safety and to allow members to practice proper group paceline etiquette, it is important to set a pace line rotation time.
Choose something along the lines of 30sec, 60secs, or 90secs. Typically, anything longer than this could lead to complacency and a lack of active communication about safety hazards within the group. It also allows everyone in the group to become familiar with the different responsibilities along a paceline (see above).
It is also good to encourage that people communicate when they are feeling too tired to do a full pull on the front and then an improvised rotation length can be implemented. If this is communicated well, this will also allow the next riders to hold a pace that allows any tired individuals to recovery.