i think the issue with fimming is that the root mass wont be there when the canopy is ready to be fimmed for 4/8. also, once you get to 4 head or greater, if you attempt to fem you could have issue retaining dominance in all the young growth tips, resulting in arms of the hub that are falling behind. you're also trying to stimulate the overall health of your plants "vascular cambium" (nugbuckets term of the day), resulting in THICK, strong branches on all 8 of the "spokes" in your ML hub, which eventually results in massive colas on all dominant growth heads.