and personally, if someone comments on one of my older posts and its relevant i tend to give them an upvote either way. Its just common decency.
I totally agree with you. The posts duration (in terms of payout) is 7 days but it does not mean that it will not add value after that. For instance this post is very useful with lots of information and I am sure it will be discovered and linked to long after its pay out.
Have a great Monday and week ahead!