Greetings, Atma. Thanks for writing to me. It is always appropriate to use the #POB and #proofofbrain tags in all your work.
Regarding the niche communities like #pobpoetry or #pob-photography, it is also welcome so long as your content is tailored for them. So, if you're not writing poetry, or your post isn't poetry-related, you wouldn't use that specific tag.
Great, thanks for answering.