I think adding gentags to posts like this is complete overkill. It's like how post #6169092 has only 9 gentags, which is mainly because of the tag limit, but adding more tags has no meaningful purpose.
If I had to add 500 gentags to an absolutely everyone post so I don't get nagged in the comments, I'd just rather not upload it in the first place.
That post has 1202 character tags, this one has 50, that's more than an order of magnitude more. Plus it runs into the tag limit, so it's not comparable in any way. Each character here has a decent amount of detail here, but the outfits are still quite simple. If you don't feel like tagging it, don't upload everyone or absolutely everyone posts then.
It’s also important to remember that some people may not know the characters’ names or have trouble remembering them. Rather than looking for “Minetsuki Ritsu,” they may be looking for “that girl from Bang Dream! with the short blue hair and round animal ears.” Adding gentags for basic identifying features like this makes it possible for less knowledgeable fans to find these characters.
It’s also important to remember that some people may not know the characters’ names or have trouble remembering them. Rather than looking for “Minetsuki Ritsu,” they may be looking for “that girl from Bang Dream! with the short blue hair and round animal ears.” Adding gentags for basic identifying features like this makes it possible for less knowledgeable fans to find these characters.
I have no strong opinions on how many tags an everyone post needs. I do want to say though that as someone who finds character names by searching copyrights for general tags fairly regularly, I avoid everyone posts because even if she's in there, I'm not actually going to be able to find her out of the 50+ character names.
As with most everyone posts, the characters in this thumbnail are so small that I'd argue even if this post is tagged to pedantry and back, users are more likely to click on it to figure out what exactly is going on in the image than out of any sort of visual recognition of gentag(s) in their search.
I'd expect an immediately graspable 1girlsolo image to teach people character names, but not this.
As with most everyone posts, the characters in this thumbnail are so small that I'd argue even if this post is tagged to pedantry and back, users are more likely to click on it to figure out what exactly is going on in the image than out of any sort of visual recognition of gentag(s) in their search.
I'd expect an immediately graspable 1girlsolo image to teach people character names, but not this.
What I mean is that if a post is searchable by a character’s name, it should also be searchable by that character’s consistent features regardless of whether the user has any intention or capability of remembering the name. We don’t necessarily need to tag the tiniest details like what color shoes everyone’s wearing, but hairstyle, hair color, hair accessories, and eye color should at least be added.
The good news is that many of these tags apply to multiple characters, so they don’t take too much time to add.