Planting seeds in groups of 2 to 50 or more (like for melons or corn) is a very old method that humans probably learned from observing what's happens to the fruits that large animals like bears or horses eat. Horses eat apples, bears too but they also eat a lot of cherries sometimes. The apples and cherries seeds will go through winter protected by the horse or bear manure and will grow in clumps in the spring. There can be from 10 to 50 little cherry or apple seedlings emerging close together. Grazing animals like deer, winter, heat and over-shading will reduce that number to the strongest and more lucky one. Many giants fruits and nut trees have been grown in that way. You can use cow manure instead of the bear manure, maybe other manures works too, the Mayan used human manure...
We plant fruits and nut trees seeds in small group of 3 to 20 or more because this allows for selection by thinning which is a very efficient method not only for trees but also for vegetables like tomatoes and melons, medicinal plants like ginseng, and many others. It also allow for losses from climate, animals, insects, diseases, overfeeding and other accidents that seedling will endure during their life.

