If you mean 6 main characters, it is not correct. It doesn't matter what Martin says and what he wants from the audience (for example, the lack of security for the protagonist while you are turning the page).The reality of the story is something else. What George showed in the Red Wedding was not a rule, but a warning that regardless of their position in the story, the characters pay for their mistakes, and yes, they can be in dangerous situations that endanger their lives, but when you read a fantasy story, you should never expect one of the main characters of the story to be killed, while you know that the character you are looking for is growing and evolving and a great task is planned for them. It will be a complete disgrace if they are killed before they fulfill the mission and duty that fate has planned for them. Besides, when you are facing the biggest threat in the entire history of humanity, expect a much more effective death and much bigger dangers than what happens just because of stupid political games. For example, you see that Robb Stark and his companions turn into mincemeat. You are probably cursing here, but you already knew that the suspicious atmosphere around the twins is not a good thing, and that Walder Frey is a sly weasel. So this whole damn thing is not something that affects the logic of the story. Instead you don't expect the Sons of the Harpy to kill Daenerys in a successful operation (or any other mortal danger) because that's a flaw in the canon of storytelling.