What has worked for me is: one-sec extension [1]. The extension asks you take a deep breath and confirms if I still want to open the app. What I have realized is I don't want to completely do away with time-sink websites, I only want to moderate my behavior of pressing Cmd-T and opening reddit/youtube/twitter in the middle of work. I have increased the length of the pause to 30 second and I am actively forcing myself to actually take the deep breath. Such a pause is enough to knock enough sense into me and return back to work. I think such kind of gentle nudging is better than being overly harsh on yourself.
[1]: https://chromewebstore.google.com/detail/one-sec-website-blo...