This scarcely matters with bonsai. Bonsai is an art form, not leading edge science that is continuously undergoing change. There is much very misleading info online where ANYbody can (and many do) pass themselves off as an expert.
I partly agree: bonsai is an art form, but operates at the intersection of art and horticulture, which does have a need for sound science. The problem lies in the number of variables involved, and to really prove anything about bonsai scientifically - as anyone in a scientific field knows - is overwhelmingly difficult. Let's say you want to prove that "Watering in the morning is best for pre-bonsai seedlings." You need a big enough "N", or number of test plants. The larger the N, the more valid your results. Let's say you decide to use an N of 100. Let's just say. So you get 300 JBP seedlings, all three years old, all the same genetic stock, all the same height, from local nursery X. They all come to you planted in the same commercial soil, in identical 3" round plastic pots made from the same batch of plastic from a local factory. You put them all together, spaced three inches apart on all sides in a rectangle in a field on your property, noting your latitude, your elevation, your microclimate, the local flora and fauna nearby, etc. You put a clear roof - made of a specified material that blocks out only certain known amounts of light of specific wavelengths - over the field, so rain will not interfere with the watering schedule. To test your variable - watering in the morning - you set up a controlled watering system using local water, and you use a specific brand of commercial fertilizer, and one third get watered at 8AM, one third at noon, and another third at 4PM, all at a specified quality of watering. You hire people to check the growth in height monthly over the next three years. You hire statisticians to analyze your results. The plants watered at 8AM did indeed grow 1.56 cm taller than the noon group, and 2.07 cm taller than the 4PM group. You think you have proved something. You publish your findings in the main journal in these matters, Bonsai Science.
Scientifically then, what have you
really proved? This and
only this: During (only) the three years of your study, with your exact set up and your exact beginning stock, in their exact pots and soil, at your exact location and elevation, using your exact watering amount and schedule and local water and fertilizer, you got the growth differences mentioned above. That's it. That's
all you have proved. With a true science, other researchers would have to then see if they could replicate your results, but they would have to do so at your site, with your stock, with your set-up, etc: otherwise those variables will change, and they will have proved only something based on their set up, stock, etc. Fights will rage in Bonsai Science for years, and at great expense, and nothing of any importance will ever be concluded scientifically about the "best watering schedule for pre-bonsai seedlings," let alone the huge questions about large trees actually placed in small pots - what we call bonsai. You simply can't get a large enough, pure enough N with actual bonsai.
Most science is like this, and the conclusions are constantly changing with more research. I have recently heard it said that about the only scientific fact that has been truly proven to date is the elements of the periodic table. There is
no "settled science" other than that! And there may never be.
As for what we know in bonsai and how we learn, I'm reminded of the poem by Theodore Roethke, The Waking. I learn by going where I have to go. Some info I learned from books and online, and some from Dan Robinson, but mostly over the years, and more and more, I learn from my trees; and that is often slow and painful and expensive learning, but it is the best. I watch them, I "listen" to them if you will, and they teach me what it takes to make them healthy and beautiful in my eyes. But that's an art, not a science, and I think that's what it's all about.