This will be random: I've just arbitrarily selected you for a question.
After ten years.....would you now say you find it considerably harder to imagine your novel's internal reality?
Laurell K. Hamilton
I've actually been writing the Anita Blake series for over twenty years, and Merry Gentry for ten years, and each book makes it easier to get into the reality of each of my fictional worlds. Practice makes me a better writer, in all ways.