Defoliation - technical term meaning to remove a ton of leaves for mostly whimsical reasons. It can be used in less formal ways too simply to mean removing some foliage. An individual's perception can make for a bit of a difference.
If you proprly managed the canopy and didn't over-crowd, there is no reason for a defoliation. Removing a select leaf to avoid condensation (or some orther high-risk issue) while also not creating a gap in leaf coverage to absorb all the light possible, is okay, too. Usually just bending or shaping the plant can accomplish the task without cutting it.
If you don't over-crowd, there is never a reason to remove leaves or try to improve light penetration etc.. More colas is not better. AFter a certain point you don't add weight, you just have smaller, more distributed buds. dli, temp, rh, and co2 levels will be the limit on yield, not number of colas. If you provide enough building blocks relative to those factors, yield is almost automatic as long as you don't do anything too detrimental.
There's really not much difference with autoflowers. Those that perceive great differences usually do crazy stuff to their plants, lol. If you put a photo on 12/12 from seed, i bet it's just as 'sensitive' to overfertilization as an autoflower. The real problem is people over-fertilize their photoperiods. I give the exact same formula and concentration to autoflowers i've grown and they look just as healthy and just as good of outcomes as i'd expect from a photoperiod with 2-3 weeks of vege time. So, obvioulsy some major holes in the perception that autoflowers need a drastically different .. anything.
why you should keep all the leaves you can possibly keep... They do more than 1 function. You may know that carbon is one of your primary limiting factors. Leaves are lungs. Less leaves = less carbon intake. It'd be nearly impossible to overcome that negative with any perceived benefit of removing leaves. This alone is reason not to remove leaves. Transpiration, light absorption, nutrient and sugar storage ... leaves are important organs to the plant. Don't remove them for bro-science reasons.
Removing leaves does not cause any magical reaction in the plant. All it does is motivate the plant to grow more leaves, lol. If theplant has too many leaves relative to its environment, it'll shed a few at the bottom. The plant knows better than you how many leaves it can maintain. Don't make that choice for the plant.
"blocking buds" is also not a good reason to remove leaves. Cell differentiation!! LEaves perform certain tasks they evolved to perform. Buds, the same... Buds are sex organs. They are for reproduction. They do not contain 1/100th of the photosynthetic potential as the top layers of a leaf. MAximizing light on buds is not going to benefit you much. Again, a non-crowded canopy should have plenty of 'light penetration.' But, don't overvalue it... leaves nearly light capture much more light (umol/s is a rate) than lower leaves. Light spreads out very fast. The further a leaf is from the light source the more significant this effect is.. lower leaves capture less light -- again, maximizing this is not going to overcome what you lose by removing leaves above it -- mathematical certainty and not an opinion.
A full canopy with no gaps and 'enough' airflow / light penetration is all you need. don't overthnk the last two parts. Stick to ~3 collas per sq ft and the rest will take care of itself. Less effort, less time wasted, fewer resources wasted on growth you prune off... etc etc so many dominos as to why you will have better outcomes, ceterus paribus, not doing bro science stuff like (mass) defoliation.
The sugar produced by photosynthesis does get used more locally than not, but that is not evidence to get light on or near buds. Sugar goes where it is needed. that's the whole role of the vascular tissue. When a concentration gradientn forms near greater growth (apical dominance dictates this, not where light hits) it draws more sugar to that area of the plant quickly. Sugar is highly mobile. Where it is synthesized in the plant is mostly irrelevant to the yield it will translate to. Based on environment, buds will be decent down to a particular depth whether they get a tone of light or not.. .again, assumes a non-crowded canopy. Most of the misunderstanding on this topic comes from the effects of a crowded canopy, which is a self-inflicted mistake anybody can avoid.
common sense -- in a crowded canopy it's gets dark pretty quickly.. at some point extreme light deprivation may have a real effect of concern.. but again.. if you don't crowd the canopy, that's not an issue, lol. I expect good buds as deep as 16-24" without purposely removing leaves to get light on lower buds (unnecessary effort). The exact depth depends a lot on the genetics of the plant in front of you, too. Stuff that is congested and mushed up against each other near bottom never turns out well.