I use a lux meter at the canopy level and 45,000 to 60,000 lux, time it by 0.015, always try keep the canopy between 675 and 900
between the leds and the canopy, there does seem to be a blanket of warm air with lower humidity, so this can cause the fan leaves to die off faster than the lower canopy, its not a bad thing because the lower bud sites receive more airflow and light.
TBH if you wait until 60% of the trichomes are amber, could be 9-14 weeks in flower, would most of the fan leaves/ sugar leaves really remain green and healthy?