A post like this takes no research; it just takes the time to think the thoughts and write the words. I don't need to fact check, find the links, explain the rules, justify my thoughts, or be funny. I just need to type. Sometimes, that's honestly all that I have the brain, or the bandwidth, to accomplish.
My current file of links to post, talk about, or use for reference is so long that it scrolls my screen three times. I've started deleting the really old ones, because they've literally aged out of relevance. But there's a new link, or two, or three every day, and I'm not removing them at nearly that rate. So something that shows up and is cool today probably is in that link file. It's just that unless it's super time-sensitive, it isn't anywhere near the top.
You know what's boring? An author blog that's all BUY MY BOOKS BUY MY BOOKS BUY MY BOOKS all the time. I have what I consider the "advertising posts," which are things like the review roundups, convention announcements, publication or sale announcements, and so on. I have the "administrative posts," like this one. And then I have the "content posts," which actually say things other than "BUY MY BOOKS" or "please don't spit on the cat." I try to maintain a good mix, but it means that sometimes, things have to wait. Since I considered both the entry on where to buy my books for the holidays, and the entry about Shaenon's party, advertising posts, I needed to do some content and administration before I advertised again. Which meant certain things needed to wait.
And that is why I do not post everything that happens the second that it happens. There's no hard and fast rule dictating what gets posted when, but time, effort, and maintaining a decent level of variety are all factors.