Two kinds of writers: prodigal v. miserly
In the trailer for her MasterClass, Joyce Carol Oates Teaches the Art of the Short Story, Oates says, “Writers are like cooks that—they keep everything in the refrigerator and put it all in the casserole. Like, what doesn’t go in for dinner tonight, well, it’s going to show up next Sunday,” then tells one of her students, “So your story has a few too many bits in it.”
Such could also be said about the art of the novel, especially if you’re Joyce Carol Oates and write one every three months (“I’ll put that ingredient in the novel I’m planning to write in the second quarter of 2023”). If you take longer to write, consider that the element worth conserving for your second novel might never come to light because you never write it. Put it in your first novel, and trust that by the time you get to your second, you will have begotten some new bits.