I run autoflowers, you chop by your trichome not pistols, about 50% of the time the top of an auto finishes first and the flower low on plant is not yet ready so i chop sequenuley to give the flower low on plant mote time to mature, get a jewlers loupe, when i see 25% amber flush out plant with cold not ice water this will help turn ur pistols, last run i had to harvest the top of plants and give the bottom another week or so, if i did not have seedlings i would have just opened a window and exposed the plants to cold then i could have just chopped at 1 time.