It does though, we can see an example of that in this very chapter
Three different speakers, all talking in flashback, with the same type of speech bubble as used in the Sanji scene at the end of the chapter. The bottom panel especially shows how Oda separates Law and Robin talking. The “your alias?” And “that’s right” bubbles are separated, despite being right next to each other, so we can tell it’s a conversation, not a continual flow of dialogue.
It’s actually when we can’t see the characters that Oda needs to take the most care in separating speech bubbles, because he doesn’t have the option of using the tail of a speech bubble to indicate who is talking.