Mine is a long form comic in two parts.
The first part, everything is planned, although there will be changes, I'm sure.
Second part has only a basic outline.
I used to have dialogue written for the next 3-4 chapters, and thumbnails done too, but I'm in the process of altering my story's structure, so that will have to be partially redone.
For me, it's important to know where I'm going, so having at least a basic outline up to the end. However, I like being able to add/remove things on the way, so I can't imagine having a very rigid frame for more than 1 or 2 chapters ahead.