Moisture

All toppings need to be considered—will they add or remove moisture? For instance, if you put raw mushrooms on a pizza, they’ll release moisture. If it’s a long bake, the moisture might release or steam off, but some will likely remain. I know you’ve had a pie soaked in mushroom water. Breadcrumbs soak up moisture. So adding them to sauce will stiffen it. Those are ends of the spectrum. Some cheeses have more moisture. That also contributes to a pizza’s moisture level. If you use a moist ingredient, you want something to soak up moisture. Or vice versa depending on your pie’s main characters. Back to those mushrooms. Why not roast them first to remove moisture and concentrate flavor, then offset that with cream sauce? You get the idea.