Seedling Bed Mixture & Management Question

Has anyone tried preparing seedling beds for vegetable crops? If so, what are your mixture and management recommendations?

In the next week, I am planning to implement Farming God’s Way (https://farming-gods-way.org) seedling bed model. You can view here:

If you have thoughts on this method, I would love to hear them.

@Lauren_Turner Here are some photos of veggie seedling beds in Guatemala in 2018. Semillas para el Futuro were using their top soil from under forest trees, sifting it very fine and adding in some sand for extra drainage. If I remember correctly they used the same mixture for the thin on ground seeding beds and for the raised seedling nursery in trays.