I do know where my saga ends, and the finale barely changed in the last years. Without it, I would not know where my scenes are going! But, I did change things in between to make the stakes higher
Yet, sometimes knowing the end means stress/fatigue: "I have to paint this part today because that's what's next, meh". Whenever this happens, I read the full storyline again and I feel super energized "I must SEE this, not just in my imagination but on paper". And I love it!
How's your creative adventure?