I don't think one can block content based on tags here so there's little reason to tag individual posts. Plus it's easy to hide NSFW content behind a labeled cut tag so it's not generally a problem. I've seen people do that.
Sometimes I have seen communities insist on cut tags or labels in the title of a post warning of NSFW content, especially if it's something they might routinely host. I know that it's a rule at the community I mod, for example, to mention if images being linked to are NSFW.
But for my own account, in the past I may have posted something that could be considered NSFW but I can't think of what it might have been. Neither my account nor any posts have ever been labeled. As some have already noted, it's pretty standard to mention it when posting a fanwork.
no subject
Sometimes I have seen communities insist on cut tags or labels in the title of a post warning of NSFW content, especially if it's something they might routinely host. I know that it's a rule at the community I mod, for example, to mention if images being linked to are NSFW.
But for my own account, in the past I may have posted something that could be considered NSFW but I can't think of what it might have been. Neither my account nor any posts have ever been labeled. As some have already noted, it's pretty standard to mention it when posting a fanwork.