Dive in time
! You mentioned earlier acid fertilizer and curious where info came from and is info set in stone?
Acid fertilizer is within the context of our crappy Southern California water with a pH of 8.0 out of the tap and super high in calcium and sodium. Other parts of the country with nice soft water may not need / benefit from it.
I also read an interesting article about root development in some of these semi-arid plants/trees. Because they often grow in rocky substrate, they will often extend roots horizontally instead of vertically. Light rains with a deep water table suggest that roots have to be shallow in order to obtain water. Additionally, these roots have the ability to extend long distances as a thick single strand, find a depression with a little humidity and extend fine roots into a pocket, and then continue on until it finds another pocket. There may be no fine roots within a certain distance from the tree, and there may be "balls" of fine roots scattered around depending on the underlying soil/rock. It is critically important to locate and collect these fine roots or the tree will usually die during collection.
Another tendency of these plants - branch die-back. Everyone talks about the presence of the beautiful deadwood on literally every plant in the wild. This deadwood can only be caused by die-back of branches and live veins on the plant. It gives the bush the character of a much older plant than it actually is. However this same character may make manzanita particularly challenging as a bonsai subject because it will be difficult to develop an apex and branching structure if the tree keeps dying back.
A last comment - there is no shortage of manzanita (in general) in this world. It is so ubiquitous in so many locations that it is considered a nuisance plant because of its hard deadwood. Branches are used in the pet trade for bird cages because the wood is so hard that most parrots can't chew through it. In its native range, it grows quickly and reproduces broadly. It also is highly resistant to brush fires and is an early colonizer of burnt areas in the forest. There are some limited species due to developmental pressure and destruction/development of native habitat. My "endangered" species is actually known locally as "Santa Cruz Manzanita" because it only grows in a small area in Santa Cruz. It is endangered due to housing and golf courses - not due to yamadori collection