When answering old questions, is there a limit to how old it should be?

Question

I'm a new user to the StackExchange network. As such, I'm trying to gain a little traction in contributing (specifically on StackOverflow). Seeing as the newest questions get sniped quickly by regular users (especially questions of the "low-hanging fruit" variety), I'd like to try to answer older questions that may not be getting any attention.

I've read one post here on Meta that asked "does it make sense to answer old questions?", and the overall answer was yes, it does. But how old of a question is worth answering? I'm aware that some old questions get automatically deleted after some period (if they have no answers). But I see a few negative aspects of answering older questions:

1. The asker may no longer be active on the site. This (seemingly likely) case results in what seems to me to be a "no-win" scenario (especially for a new user trying to gain reuptation), as the answer will likely never be accepted.
2. The question may be old enough to be out of date. I imagine that the auto-deletion of unanswered questions prevents this to some extent, but how old can a question potentially get? And what should a new user do about questions that may no longer apply?

Am I missing something obvious here? Is perusing the older, unanswered questions for topics I'm interested in a good starting place for a new user? As I mentioned, new questions are snapped up too quickly (in my opinion). This is obviously good for the asker, but it makes it hard for a new user to get any traction.

Answer 1

A benefit of answering an older question is for other people on the Intertube (or SO) who are looking for a solution to the exact same problem. If they Google their problem, and find that old question you have answered, and your answer satisfies them, then you have helped the community, even if you didn't get directly rewarded.

Answer 2

If a question is still broadly relevant today, what does it matter when it was asked? The most important audience for your answer is not the asker, but the (hopefully) many people in the future that will search for a solution to that same problem.

In fact, you can often find some very good unanswered questions that are a year or so old, because once you fall out of the one or two day window where most people look for things to answer your odds of getting an answer drop off rapidly. The Community user tries kicking a few of these older questions up to the top of the list from time to time, but there are still many good ones hiding back there. Some of these never got answered simply because the people with the expertise had not yet found the site, they got asked on a weekend, or some other reason.

With badges like Revival and Necromancer to incentivize the answering of older questions, this is behavior that is clearly encouraged.

I've seen a very long tail on many of the older questions I've answered, with votes for these answers coming in once every few months over a period of years. This clearly indicates that answers have lasting value to searchers, long after the asker has lost interest in the problem.