Writing a novel fast requires focus and discipline. Eliminate distractions, write in blocks of time, and don't get bogged down in perfecting every sentence in the first draft. Just get the story down.
Well, it could be related to some sort of power - up or inheritance in the fanfiction world. Maybe Naruto discovers a hidden bloodline trait that not only gives him new abilities but also enhances his learning capacity. So he can quickly grasp new jutsus and combat strategies.
One way to do it is to plan your story thoroughly before you start writing. That way, you know where you're going and can write more smoothly. Also, limit distractions and set a timer to keep yourself focused.
One way to write a good novel fast is to have a clear outline before you start. Know your beginning, middle, and end. That way, you won't waste time deciding what comes next.
First, come up with a strong central character. Then, have a clear beginning, middle, and end in mind. Don't overthink the language; just get your ideas down. Cut out any tangents that don't contribute to the main story.
First, decide on a clear theme. Then, make a quick mental map of the plot. Start writing and keep the flow going. Don't stop to correct mistakes until you're done. That's how you can write a 500-word story fast.
The key to writing a fiction book fast is to have a clear outline before you start. Know your main plot points and characters. Also, set a daily word count goal and stick to it.