just a small reminder as I know another developer had some troubles with this have a baseline planned for what you want (i am assuming you already have that) then when ever you are gonna add a new character think whether they will be extras or main story characters if main story think of the possible extra work. If you want to know the developer I am talking about they are the Bloom Wars dev and the point where they talk about this type of thing is in the Patreon thing (its free don't worry) back up and running
Thank you for your advices. I am indeed a specialist (not only in game dev) for not planning enough for the long term. At the moment, I know globally until chapter 2 where I want to go. I'll see then if people want me to continue.
Many thanks for having taken the time to give me these good advices!
PS : Bloom wars is a great game by the way.