I actually meant to bring this up with mk and you- if I share an old post, I don't think that it jumps back into people's feeds- the things which make it decline based on time posted make it still very irrelevant. I think instead of caring about when something was posted, it should jump based on how recently it was interacted with (shared or commented) and the extent of that interaction. Does that make any sense to you guys?
Here's the new algorithm in a nutshell: Posts are listed in your feed according to their score. The score is 1 by default. It falls off to 0 with time. Every time it is shared (or badged) a bit is added to the score, and then it is fed back into the decay equation. So even if a post is really old, a single share should bump it into people's feeds. This new system should be integrated into the site code in the next couple days. We'll see how it works. I'm very proficient at math, but not at computer code, so it could be a train wreck.
Makes sense to me, I'm not sure as to the best way to rectify it though.
Instead of declining based on time since posted, make it decline based on time since it was interacted with, which is an actual measure of how bored people are with a topic.