Oh, all these pictures except the very first one were taken just after decandling. When they pretty much look their worst! Around Thanksgiving, they'll have hardened off new summer candles, and should appear 3 times as thick! Each twig generally produces two new summer candles, so add that foliage to the existing foliage, and that's triple!
If I'm planning to show the tree in the next six months, I'll leave most of the old needles on. Trees look better when they're full.
Otherwise, pretty much all the needles you see on these trees will be pulled in November. Leaving only the new ones that will have grown between the time these pictures were taken and November.
Why pull the old needles? 1) it makes it much easier to wire. 2) it opens up the interior of branch and lets light in. Which stimulates backbudding. And 3) aids in keeping it insect and disease free.
Be aware that pulling old needles destroys any potential needle buds! So the backbudding we will be getting will be from old dormant adventitious buds.
So... If there are places where you DO want needle buds, don't pull those needles! Just know that needle buds are very unreliable unless the tree is very strong.
The fat sumo pine, the very first picture in this thread is very strong! Last year, it actually put on three flushes of growth. Spring, then summer, then fall! Not all over, just up at the apex. So when I decandled this year, I cut back into that second flush. And I've gotten about two dozen needle buds making long summer candles! Wow!