My experience is that when you have enough assets, a good estate planning attorney puts the assets in a trust when one spouse dies. The trust is owned by the children, but they can’t touch the money until the second spouse dies. In the meantime, the surviving spouse is entitled to all income from those assets until they pass.
That is how my step dad sets up his clients, and all of our family. It ensures the spouse has the means to live well, and that the kids are protected from a new marriage.
There are different ways to do it. My mother-in-law’s husband allowed her to use his money for living, transport etc. and when she passed, it went to their church.
He had told me that the kids wouldn’t get anything and remember telling him that I wasn’t expecting anything. My brother and sister in law don’t have much and did get something from their mom’s estate as did my wife.