I don't know if I've seen any other subject besides politics and pruning, where the experts and people we look to for guidance can so disagree on fundamentals.
I can't say most of them are wrong, but approaches can be quite contrary. I've read hundreds of articles on most aspects of pruning. The only thing I can do is try to understand where they're coming from, see if there's a consensus, throw out what doesn't make sense, put some logic to it, apply personal experience, and in many cases think outside the box.
I believe that most writers on the subject realize that teaching someone all about pruning within a short article is really hard without the reader losing patience. And the reader may have little, if any experience on the subject. Because of this, most articles really tend to dumb things down to the point where the student can't screw things up too badly or poke their eye out or fall off a ladder or cut their finger off, but they miss the mark on some of the finer or more confusing points.
You should also understand that most people simply ignore their trees for extended periods, then over-prune to make up for it. I never recommend this, but since it's human nature, the guides tend to reflect this approach.
You'll see most articles focus on how to cut properly, but spend less time on where and why to cut or not cut this or that, and consequences of every cut. I find that the instructions on how to cut are usually accurate and quite good. Since you can find these instructions everywhere, I tend to avoid spending much time on that. I spend much more time preaching about the where, why, and when.
I see perhaps the most confusing subject is when to prune this or that. You'll usually see it mentioned that most trees and shrubs should be pruned during late winter, early spring, or summer, depending on the specie, when it flowers, and your goal. I rarely see anything mentioned about how your climate affects this timing. This is puzzling. If you live in Miami, shouldn't your timing be different than if you're in Fargo? Maybe it doesn't change that much with certain species, or a specific tree simply doesn't grow in your location, so the point may be meaningless at times.
Plenty of articles deal with timing your pruning for maximum flowering or fruiting benefit. They're pretty much on the mark, but they don't deal with some finer issues about pruning throughout the year, which I write about a lot. Many articles deal with trees that are problematic, either because they catch disease easily or bleed heavily b or respond to pruning in notable ways. But some of this advice may be contradictory. For instance, pruning a birch or elm during the summer may be best to avoid bleeding or water sprouts, etc., but the cuts can attract well-known pests that can kill the tree. So it seems most articles reflect the better decision, though you have to learn more to make the right decision. Once again, as I can't mention often enough, frequent, minor pruning is much better than infrequent, major pruning.
I have a post or two that deal with timing. My rationale is a based on many hours of research, and as things progress, my approach may change somewhat, just as it may change from one individual tree to another of the same specie.
Regarding thinning, heading back, topping, pollarding, Crape Murder, butchery, etc. I have very strong feelings about all of these treatments and those opinions run rampant throughout my posts. Be very careful while watching videos. Much more often than not, the ones that claim to show you the right way, don't.
Isn't this fun?