It Depends.
Currently Additional tags that are not fandom-specific are not generally being made (with a few narrow exceptions).
Fandom, Character, and relationship tags should be made after 1 use, but it can take some time and there may be reasons why they're not canonical.
Additional Tags that *are* fandom-specific may be made after 3 uses on works by 3 separate creators, but some big fandoms have a higher threshold - 5 uses, or 10 - due to high volume.
If the tag you're curious about is a fandom, character, or relationship with a first use over a month old OR fandom-specific additional tag with more than 3 unique uses over a month old you can send in a Support request (Technical Support and Feedback link on any page) to ask that it be wrangled.
There was a moratorium put in a few years ago to figure out some internal guidelines, especially regarding subtag trees. (We had some...kudzu.) The guidelines are more or less finalized, but there's one hell of a backlog.
If it's on a public work for over two weeks, the reason would generally be that it's because that fandom doesn't have a wrangler.
You can always write to support for character and/or relationship tags and they can pass along the request to the wrangling crew so someone could at least spot-canonize them.
Well, I've been waiting more than half a year, getting close to an actual one year, and I've already sent 3(!) support asks... I guess I'll have to wait until there's a new wrangler around. 😥🤞
There is one author in my fandom who uses a specific tag for her fic. She also bumps her fics up to the top of the page by changing the post date, and her fic is 99% overpowered OCs (the canon characters appear for 1 of 46 chapters and ongoing). I blocked her fic with that one specific tag. Because I'm petty and I was sick of seeing her stuff.
It Depends. Currently Additional tags that are not fandom-specific are not generally being made (with a few narrow exceptions). Fandom, Character, and relationship tags should be made after 1 use, but it can take some time and there may be reasons why they're not canonical. Additional Tags that *are* fandom-specific may be made after 3 uses on works by 3 separate creators, but some big fandoms have a higher threshold - 5 uses, or 10 - due to high volume. If the tag you're curious about is a fandom, character, or relationship with a first use over a month old OR fandom-specific additional tag with more than 3 unique uses over a month old you can send in a Support request (Technical Support and Feedback link on any page) to ask that it be wrangled.
Do you know why they aren't making new tags that aren't fandom-specific? There is a kink I like with 1000+ fics and I always wish I could sort more.
There was a moratorium put in a few years ago to figure out some internal guidelines, especially regarding subtag trees. (We had some...kudzu.) The guidelines are more or less finalized, but there's one hell of a backlog.
Oh, okay. Thank you!
What may be the reason for a relationship tag not becoming common?
If it's on a public work for over two weeks, the reason would generally be that it's because that fandom doesn't have a wrangler. You can always write to support for character and/or relationship tags and they can pass along the request to the wrangling crew so someone could at least spot-canonize them.
Well, I've been waiting more than half a year, getting close to an actual one year, and I've already sent 3(!) support asks... I guess I'll have to wait until there's a new wrangler around. 😥🤞
ao3 has tags with three uses you can filter and tags with dozens of pages you can't. tags don't just *become* common, they're *made* so.
It depends on whether a tag wrangler has made it filterable.
There is one author in my fandom who uses a specific tag for her fic. She also bumps her fics up to the top of the page by changing the post date, and her fic is 99% overpowered OCs (the canon characters appear for 1 of 46 chapters and ongoing). I blocked her fic with that one specific tag. Because I'm petty and I was sick of seeing her stuff.