You have to do like 3 rounds of lollipopping in flower because they just grow back. I do what looks like a good lollipop to remove lower crap growth a week before flower. By a week or two after flower most of it has grown back and the top canopy is longer so you have to cut it out again. It helps to do it a last time 4 weeks or so in flower. I like to make edibles so I just save mine but I've never been able to lollipop high enough to prevent all of it. Usually 1/4 to 1/2 my harvest is popcorn and trim.
max number of plants . under a 600 in my opinion is 8 . 3 gallon pots . 2 rows .. with a large hood . i dont get popcorn . . in my set up with 8 per 600. you just need to trim the lowers better . once you learn what branches produce those popcorn . the next grow you know what ones to trim off . problem solved . why your getting the popcorn there is just not enough light to the bottoms of the plants . trimming those branches off producing popcorn will allow the plant to use its energy to make those mega buds ! . and dont for get to super crop all the tops about week 3.5 to 4 in flower . if you want more info on super cropping just ask . now if were weighing these p.m.a .... cherry tomatoes you should get 3 ounces of tomatoes off each plant . so its 24 oz off each 600 watt light . not to shabby right . p.m.a . = protect my ass . how long you veg will add the amount of trimming needed . what i like to use 8 or 9 inches veg plants that are topped max height then flip to your flower . hardly any trimming . hate to see plants on stilts pisses me off . just a long ass stem pointless lot of people do it waste of time in veg . finish height of 20 inches or so .