We put in a new front page formula this year, and it's definitely improved this area. It used to be stagnant, saves would appear for the maximum 1 week period and lots of other potentially good saves were left out. The new formula looks at the pool of all eligible save and randomly rotates them every 10 minutes or so. The highly upvoted saves stick around. Even those saves do get swapped out often, but they always come back if they have the votes.

So overall, you will see a lot more saves than you used to. If some don't deserve front page, you can downvote them. Do remember that there's not an unlimited supply of saves out there. Every save is competing for slots, and other users may have different taste than you. So it's expected that not all 15 slots will be taken up by saves you like.