Pinning follows the development of the crop and the change to suitable fruiting conditions. Review compost and casing development first. Then follow the strain and crop programme for air, temperature and moisture together. A sudden change in ventilation also changes drying and cooling, so treat the room as an interacting system rather than a set of independent switches.
Map the response. Pins only near the door, drying along an air outlet or delayed patches on one tier are useful patterns. Compare those locations with air distribution, casing depth, watering and bed measurements. Record the time of an adjustment and assess its effect at the next planned observation. Avoid repeatedly changing several controls because pins did not appear on the expected date.