You mean you actually write them! There's an interesting idea.
Yep, I'd recommend that. You can always rewrite it later. It's a nice problem to have in a way. You know where you're going. Unless you change your mind.
I remember with the Prospero book, the scene that was in my mind forever was one of Rachel talking to the Elf on a balcony. I ran this scene over a million times. Since the book took me years to write, I remember the astonishment I felt when I finally reached it and actually had to write it.
With both the Rachel and the Victoria books, there are scenes like that, too. With both of them, they always seem to be scenes many books in. But in both cases, I have the notes from the original game, so I'm not sure I need to write more until I get closer.
...This is a fascinating comment in terms of how differently people can think. The obvious thing to me was to go ahead and write them, and I therefore imagined that you had deliberately rejected that option and were resisting the urge!
I have written a scene ahead maybe once in my life. Basically, if I haven't gotten there yet, I don't know what the tensions are that will make the scene work, so I can't really write it.
It just doesn't feel right, so I hold the scene in my head.
I have written snippets of dialogue ahead of time. And long notes when I don't already have any, but not scenes.
In this case, I could write the scene because I do know a lot of the surrounding info...but I probably won't...;-)