You can always change everything in the story and republish or update it instead of creating a new story If the characters aren’t in the style you wanted, then you will need to create a new story…
This is simply because 400 lines goes by in a flash, for example if you wrote at least 1000 lines, that’s on about a five minute episode. Everyone must have 400+ lines even if it’s not that long
most people don’t they just put a blank and they make it only 200 lines
Correct. If you want to, but most readers prefer a longer episode to grasp the stories consept.