I cannot quit cold-turkey because all the methods that I can think of to block the websites I can undo in the mania of anxiety.
Youtube always gives you an option to look for more content, either on the side of the video you are currently watching, on the screen immediately after you are done watching or by going to the home page and giving you the options. Using Origin ad-blocker I removed all the immediate suggestions. And also the youtube home button, the only red element of the Youtube gui that catches your notice, that you click on to reduce your anxiety. That you then develop a habit on, just like the suggestions. On mobile I uninstalled the app and used the ad-blocker to render it useless. All external links play videos and the search still works.
For reddit I force the old view, without the infinite scroll, just like the author. I also removed the 'all' link from all the pages as I had formed a habit with that as well. And I limit the number of posts visible at any given time.
I have, other than the author's solution, no counter for HN.
For other websites, I've similarly blocked such habit forming gui features. And the most important bit has been deleting websites from the auto suggest feature of firefox. I've deleted a good number of the common offender websites form it, but I still don't know how to disable those ~10 websites that show up when you go to type something.
The Key has been disrupting the 'cue' of the habits. It leaves you a little confused when you don't find your habit enabler on the websites, but then it gets better. Or like me you form other new habits. The solution author suggests will definitely be of help.
Edit: Words. Also, does anyone know how to disable the dropdown suggestions in the address bar? The one you get when you haven't typed anything, because I've got a habit with the dropdown button as well. There is nothing in the options, but what about the developer options?