Okay, how long is it okay to leave a reader in the dark about details in a plot? For example, if one were to use media ras(start in the middle of things just in case someone isn't sure about that), how long can one write a plot without telling the reader about it? Is it okay to perhaps never tell the origin of things? I know in horror stories that a lot can be left in the dark, but how much? In a non-surrealist plot, how much can you keep completely in the dark? Very curious about this.