Sometimes, older stories receive new attention when the author shares the link in their profile. I've actually had an old story of mine appear in the top 25 stories for a few days due to newly generated interest.
As far as trending? It has always appeared that it is constantly changing. I've had older stories trend for a bit when new readers are checking it out, and an hour or two later, it's gone.
My stories are not nearly as popular as many of the authors here if you go by the numbers. (The only reason I'm the top author of all time is that I have published over 500 stories on Lush). But I prefer to focus on the comments. What people say about my stories makes me feel like I've done what I've set out to do. When I want an older story to get seen by new readers/followers, I post the link in my profile with some cutesy message. It makes me feel good that a story I enjoyed writing is being seen by new eyes.
As for those who think being on the front page for an extended period of time helps promote views, you should know that this isn't the case in my experience; it's a crap shoot at best. My most recent story sat on the front page for the better part of 24 hours, and it's doing okay, but not gangbusters, which is okay. Ultimately, I write for the joy of writing and to, hopefully, entertain readers with my vivid imagination. Sure, it's fun when a story catches a lot of attention. Who doesn't like a pat on the back? But I can never really predict what will be a "hit" and what will "fizzle," and there's no rhyme or reason or algorithm that explains that.