Also, old posts never disappear from the site, they just fall off the front page. You can use the search feature to find stories that interest you, no matter how old they are:
How are stories ranked?
The basic algorithm divides points by a power of the time since a story was submitted. Comments in threads are ranked the same way.
Other factors affecting rank include user flags, anti-abuse software, software which demotes overheated discussions, and moderator intervention.
I recommend you to check Hacker News Daily [1] because it summarizes top stories on HN daily. It also summarizes Ask HN, but weekly [2].
I think you don't need to check HN frequently. If you miss a day, you can always go back or jump to date using Past page [3]. Other user has mentioned tools, like hckr news and HN Search using Algolia.
Oh think I check too often and I see mostly the same stories over and over. I frequent the front page and ask.
What I would like is a hide feature that knows what posts I've looked at and removes them from the ui automatically. Bonus if I can "lock" the post and prevent it from being hidden because I want to continue to monitor the thread, or click "hide" on a post I'm done with or uninterested in. Noise reduction allowing me to quickly seep what is new to me.
There are a lot of good posts that never make the front page. Staying up with the "new" section can be time consuming, kinda depends on the day. I usually check in most days.
Downvoting buttons disappears after a day, upvoting never. One can comment for 14 then, after that the 'reply' link disappears.
If you want more/faster stories use the 'active' list https://news.ycombinator.com/lists or 'new'. If you want to check less and not miss good discussion use https://news.ycombinator.com/best
There's twitter account which only tweet stories which got at least 250 upvotes https://github.com/adriel/awesome-hacker-news#social-media