TL;DR: Stack exchange incentives discourage answering/improving old questions that have an accepted answer. Would highlighting new answers help with this?
I've answered 2 questions that were over a year old and already had 3 or more answers. In each case I did this because I thought I had a substantially better answer for games in which I have a lot of experience. The mechanics of stack exchange make new answers buried beneath many other answers and thus not noticed. The new answer is unlikely to be accepted as the question originator is often no longer participating in the site, or even if they are don't get voting information to help decide if the new question merits acceptance.
Stack Exchange was initially conceived for developers who had objective questions with typically one objective answer. But the way Board and Card Games has evolved, questions about strategy are popular and typically have multiple possible answers. Furthermore, rules change over time which can change the correct answer to a question (see What to do when an answer is no longer correct?). As rules change, and more importantly as new people join the site who may have different (and sometimes better) strategy ideas, it would be great if there were a way to temporarily highlight a new answer so it could be seen and considered. If not bubbled to the top, perhaps a brightly colored link to the new answer that lasts for 3-6 days. This would provide an incentive for people who think they have a potentially better answer to post it to an older question - they'll know that there's a real chance people will see the answer and vote/comment on it.
What are good placement strategies for Stratego? (I believe I can beat someone who always uses the strategy of the top answer at least 80% of the time, so I provided a competing answer)
What are the key strategy differences between Settlers of Catan and Seafarers? (I agree with the top answer but it is not even close to comprehensive, so I provided a more comprehensive competing answer)
Based on the reception for my answers to these questions (few views, few votes, no comments), I am inclined to not answer old questions in the future (that have more than 3 answers already). I would imagine more seasoned participants figured this out long ago and never bother trying to come up with better answers to old questions.
I'd like to hear from others whether it makes sense to highlight new answers to old questions (at least temporarily), thus providing more incentive for people to come up with better answers to old questions. This could lead to more improvement in older questions than currently happens. Obviously, if most people feel this would not improve site quality, then it's not worth doing.