I think this tag is only really useful on newly released doujin, that sneak preview is going to make the readers wait in anticipation for the next one. Older doujin meanwhile are "meh, what's the point when there's already that new doujin available?".
Besides any case where this tag proposal might be useful, the real problem is maintaining the tag in such a way that someone is going to manually check and label the end of every newly released doujin (because sources like e-hentai will not do it for this website), which frankly can be a pain in the ass to do. If there's going to be at least someone who will dedicate oneself 24/7 to that task (even check the doujin with tags that person loathes and abhors) then sure let's have this tag.
@fuckriri1234 what bloat? We have shot over 1000+ suggestions already. If we go into the bloating argument then there are surely the "suggest a tag that's already existing" which are the more pressuring issue before this tag here.