For me defoliation is usually a question of when and how much, as I think some amount is almost always beneficial, and I evaluated each plant individually. The advice from Hashsloth is right on point. By late flowering my plants usually have few to no fan leaves, only the ones blocking no bud sites usually on the perimeter of the plant remain.
I don’t remove them in one or two passes, but a few at a time starting at around the end of week 4. I do lots of leaf tucking as well but will remove a leaf when it can no longer be easily tucked or is casting shade on developing bud sites. It’s true that fan leaves do store sugar and nutrients but in a highly controlled indoor growing environment, I am just not sure that matters very much. My plants are on hydroponic life support via coco coir and always have a fresh supply of nutrients and sugars in their nutrient solution.
This wades into the territory of observational bro-science, but I believe the fan leaves are absolutely essential from sprout most of the way through the stretch. By mid flowering the buds are usually growing so large that keeping any number of the fan leaves on the plants simply becomes impractical if you want to get the best light penetration to bud sites. By this stage the remaining fan leaves seem to behave more like silos than solar panels, but since my plants always have a fresh supply of nutrients in the medium, they don’t need the fan leaves doing the same job. At this point the buds also have plenty of their own leaves that power continued bud development.
Keeping N levels in check is another way to manage leaf development during veg, and of course some strains just leaf out more than others.
You can find infinite opinions on defoliation, this is just my approach.