The most important part of a good tres leches cake is the sogginess factor. You want to have a very wet cake so that when you cut into it, all the pieces cling together with thick sweet milk syrup. The cake itself should not be soggy, but rather saturated with three kinds of milk . It's more of a "dry" sogginess than a "wet" sogginess. If you prefer your cake to be more on the dry side, reduce the soaking time by 10 minutes and experiment with less milk in the soaking mixture.