It depends very much on the topic. Something that can be approached with analytical rigor or determined completely through a few tests can probably be written

It depends very much on the topic. Something that can be approached with analytical rigor or determined completely through a few tests can probably be written by diving in and learning everything while you write. Personally, I write technical articles mostly to cement things I just found out in my own mind and I have often found that in my testing and writing I learn things creating my articles that I hadn't known. But more ephemeral topics benefit greatly from experience. When I was in the military, I benefitted greatly from the experience of my NCOs and much of what they passed on to me where things that would have been very hard to put into a book or discover through any process other than experience. But I suspect most technical topics fall into the former category rather than the later.