I flag the posts that I consider aren't useful for the page and always the flag says "helpful", but sometimes the flags aren't validated and they become "aged away". How can I avoid my flags become aged away?
Not all types of flags can "age away". According to Meta Stack Exchange these are the only types:
- Spam and rude/abusive flags on posts age away after 2 days.
- Rude/abusive flags on comments age away after 4 days.
- Migration close flags (and votes) age away when the post can no longer be migrated (i.e., when it is more than 60 days old).
- Close/reopen flags (and votes) age away at latest 14 days after the newest close/reopen vote.
The first two types of flags are immediately brought to the attention of the moderators.
In my experience, spam and rude/abusive flags on posts are dealt with fairly quickly. When present they are highly prominent in the moderator flag queue, and I make it a personal point to prioritise dealing with them (and I'm sure I'm not the only one). It is highly unlikely that these would age away.
Comments are something generally easy to deal with, and I don't think too many rude/abusive flags on comments are left for long periods of times. I have no statistics on this, unfortunately.
The last two types of flags aren't specifically brought to the attention of the moderators. Instead they bring posts to the review queues for community evaluation. If these sorts of flags age away, I would generally take it that there isn't broad community support/agreement with the action you proposed. Part of avoiding aged away flags of these sorts is becoming knowledgeable with the norms of the community.
All in all, I wouldn't worry too much about aged-away flags. Sure, it could be interpreted to mean that your flag wasn't clearly valid, but more positively it can also be taken to mean that your flag wasn't clearly invalid.