The method that you posted doesn't actually open the post where you left off. If a thread gets a new reply, then the ".new#new" url would lead you to the last reply of that thread instead of the actual post where you left off.
In order to achieve the same, here are the steps :
1. Click on the post form where you want to continue later as shown :
2. The url that you land upon must be bookmarked
->
Sorry mate, but it always lands me to where I left
This is so clear. It's impossible for me to say it twice. Beside that the other way is you remember what page you commented in thread. You can use it like this
https://bitcointalk.org/index.php?topic=2945878.
52The number behind the drop lead you to that page but not directly to your column. (Hope you understand)
Anyway Did you ever tried a thread that have many comments, it will helps you solve the meaning.
Because .new#new will just bring you to the last comment or newest