I think where a tree spade would be beneficial too is when i have leftover trees from spring planting and replacements i could plant them in an area until i am ready for them. I've tried it before and after a couple years digging them up with a shovel and transplanting but i don't think i took enough of the root ball and they died or i did it to late in the spring.
in the pic you can see the food plots i have on the right side. the rainbow lines are all soil conservation planted trees and the 5 pink ones are planned continuations of the rows. I have hand planted a few thousand trees in the pasture but they are sure slow to take off without fabric and care. easy to see all the junipers and cedars when it's grazed down though.
Soil conservation, from my experience, plants trees about twice as dense as they should be ideally. I think they expect a fair amount will die from neglect or whatever. I like the look of a tree that has room to grow more than that of trees that end up growing into each other after 10 years or whatever. On my land, there is a clay layer thats down about 16 to 18 inches, pretty consistently throughout most of my property, the clay isnt thick, about 2 inches or so. Problem that happens often is that some trees roots hit this clay layer and then grow sideways because they arent able to penetrate. Some plant roots will penetrate clay, both others cant. Then, if you get a dry year, your trees will just die unexpectedly, because they cannot access the deep moisture thats needed in drought conditions. If you break that clay layer, trees that otherwise might not send deep roots, will be able to keep growing down and will have water available when they need it. This might not be important for everyone, it just kinda depends on your soil situation. Also, if you have a clay layer, it can cause water too pool in an area instead of draining away, which can kill trees as some trees cannot handle setting in water for a week or two. Breaking the soil does help with establishment and also makes planting a lot easier if you are doing it by hand. What I do typically is rip the soil, then harrow drag it and maybe till, depending what Im planting and how I want it to look when Im done. Tilling isnt as important, but if you want to incorporate some fertilizer into the soil, its not a bad last step. You could also put down some fertilizer before dragging it also if you dont have a tiller available. Just dont throw fertilizer on top of the soil and expect it to help your plants much, unless its going to rain for sure shortly after you put it down. Ripping also aerates the soil, more o2 = happier roots = faster growth.