On the machine where I read meta, I have four tabs permanently open, and others open when needed. Pretty far from infinity, but yeah… I never close the Discourse tab.
However, let’s say I used that setting. I am gone for a week, and during that time 50 new topics are posted. When I return, I open a tab and navigate to meta, and it shows me that I have 50 new topics. Life is good.
I start reading some of the topics, then go off and do something else, and when I come back I accidentally close the Discourse tab. When I open a new tab and head over to meta again, what will happen? I really don’t want to be obligated to process all new topics in a single session without making any mistakes, because I am human (others may disagree).
I think that having a reasonable length window for topics to be considered new will solve this problem, and 7 days has been working well for most situations (weekends, even long ones, or really busy times at work where I can’t visit meta for a few days, even though the tab is open). It’s just that occasionally I’m away for a longer period of time. I do agree that going beyond 2 weeks would likely be wasteful, as if I’m gone that long the new topic volume would likely be overwhelming… but on a less busy site, it could be manageable.
In the interests of trying to help solve the real problem, how about if we had a setting that required explicit action by the user to indicate ‘here’/‘not here’ status to Discourse? If Discourse assumed I was ‘here’ until I logged out, whether I close tabs or not, that could also solve the problem, because then ‘topics created since I last went away’ would be perfect. It’s slightly different from ‘when I was last here’, but close.