The "View Posts Since Last Visit" option is non-discriminatory and far too general in that it shows results for every active thread, so you can guarantee a lot of it will be completely irrelevant to your interests.
It does exactly what it says, globally, and because it's so general I never use it.
What follows is the method I use and is as seen in Firefox - but the actions should be recognisable and similar for other browsers.
First, ensure your browser setting has the option "When you open a link, image or media in a new tab, switch to it immediately" unselected. That might be described as the inverse - open a link on a new tab in the background (what we want). The idea is that the browser won't move to a tab opening a new link.
The option "Open links in tabs instead of new windows" should be selected, and new tabs should appear to the right of any existing tabs and not next to the one you're currently on.
1. Start from the forum index page here - https://wrongplanet.net/forums/
2. Look at the index and decide what forum you want to look at - say, News and Current Events.
3. Click on that forum using the right-hand mouse button and select "Open link in new tab".
4. Move to that new tab, now showing the index page for News and Current Events.
You can either choose something of interest or a topic having recent posts - they're displayed in date order and it's easy to see who posted last & where.
5. Click on a topic of interest using the right-hand mouse button and select "Open link in new tab".
6. Select another topic and open it in the same way, until you've worked down the index and seen enough.
You'll have constructed a stash of topics of interest.
("Topic of interest" can also mean the last page of a busy thread, the "Go to page:" list - they're just links to specific pages in the topic)
7. Click on the rightmost tab (the last topic of interest you selected) and read or post to the topic you'd selected for that tab.
When done, close the tab. The browser will now display the next tab to the left of the one just closed - your second-to-last topic of interest.
8. Work your way back through the tabs from right to left, closing each one as you go - eventually you'll end up on the tab showing the index for News and Current Events, where you might like to have the browser refresh the page to display any recent goodies that were posted while you were reading the topics you'd first selected.
Open those as required, as above.
9. Eventually you'll be done with News and Current Events so close that tab too - you're now back at the forum index page at step (1) above.
10. Rinse and repeat - choose another forum and work through any topics of interest in the same way.
I find "right-click | open link in a new tab" is very useful in a number of situations - a link for a thread included in a post, the link for an image, the image itself, the link for an off-site article and so on.
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Giraffe: a ruminant with a view.