Hello Anon! Welcome!
To answer your question, there isn’t a set rule about that. We all reblog photo sets and post that relate to our character in canon. For example, we usually reblog photosets of the characters we play. We also will usually reblog gifsets of characters that matter to us (i.e. Wendy might reblog gifsets Bae and her brothers), but usually only if the character is aware. For example, I don’t reblog gifsets of Bae in the Enchanted Forest or Neal in our world/Storybrooke/Enchanted Forest. I would only reblog photosets of him in London with the Darlings or in Neverland after we were reunited. There is the exception to that if a photoset is dedicated to that character. For example, if a gifset was focusing on something about Bae’s personality or just an appreciation post for him that included photos both in his time with me and not.
I hope I helped answer your question.