I remember in English class, there were special formatting rules for if a character talks for more than four lines. I think my school hated fiction. Also, I think the teachers were still caught in the phase of word-processing and not being able to change font sizes. There is the obvious questions about modernizing the rules, or if they apply to fiction. If fiction should have monologues. I'm also fanficcing for a game where many of the voice-actor outtakes are jokes about monologues.
There are no special formatting rules for long pieces of dialogue. Well, the only rule I think you should be familiar with is if you split up dialogue spoken by one character into multiple paragraphs. You use opening quotation marks for each paragraph but only use closing quotation marks for the final paragraph. For example: He began speaking. "This is a very long speech, so I'm going to split it up into two paragraphs. Notice that this paragraph does not have quotation marks at the end because the same character is speaking in the second paragraph. "This is the second paragraph. Because this is the final paragraph in my example, it does have quotation marks at the end. The logic behind this is that you don't have to keep identifying the speaker each time you start a new paragraph."
i know of no limit to lines of monolog/dialog other than in screenwriting, where more than 5 is considered the verboten 'too much black'... which also applies to lines in the action/description element... in prose, you can make it as long as it need be... but it does need to be done in a way that won't put the reader to sleep...
