It's almost the norm for threads to be into the hundreds or thousands of posts these days. For me, I'm actually more likely to click into a thread with like 20 posts on it because I know I can read it all. 200 posts in a new thread is daunting. 400 new posts on a thread I haven't visited in a while generally means I'm not going in there anymore because I'll never catch up. And even if I do catch up, I'll probably end up in the same situation down the road.
I know that key posts is/was a thing, but most threads have 0 and occasionally I'll see 2 or 3.
I think I'd be interested in condensed threads with just the highlights. The best thought I've had so far is: use the top 5% of posts in a thread as calculated by total thumbs up and down. (I think that way, you'd see the posts with the most thumbs up, most thumbs down, and most controversial ones. Basically, the ones that generated the most interest/reactions.)
Would this feature add value for anyone else?