here's a simple explanation of what i believe is the best route. Defloliation is needed when plant count exceeds amount of space they should be in , in order to properly train them.
If things are properly planned out , defoliation is unnecessary because the trained plants will take up the appropriate amount of grow space. This is what you ultimately want because it means way less work, just feeding and tying.
when a plant is trained correctly to use up however much footprint / light depth there is, the oscillating fan will wiggle those fan leaves and all those lower bud sites still get light. The fan leaves are the best cause they really make sure that you're getting every bit of light possible, and on top of that the fan leaves act as an extra source of backup energy for when there are deficiencies, and the deficiencies no longer effect the buds but just the fan leaves. If a fan leave is 40-60% damaged i take it off, and i usually catch them before they fall off. I throw out any dead fan leaves so i don't attract extra bugs, and usually only the very bottom fan leaves die off. I try to give my plant enough N throughout all of flower but not a toxic amount, right on the border of about to yellow up towards the last few weeks and then a 2 day flush cause it's coco
sometimes if the bottom 3" or so has leaves on it ill cut them just so air can channel under the leaves a little better
my input on the matter, hope everyone is growin some dank!