"Bonsai (though this is not the only factor, I believe it to be the single most important) and with lots of trees, observation that would take many years with only a few can be compressed into a few."
Hi Fred, Yes I agree with that totally. The more trees you have and the more things you do to them the better you'll know what "possibly" can be done with them and what their response will be to certain stimulus. Books are good but they cover just a few of the species that you'll be wanting to try. That pretty much leaves you with trial and error to see what will work. That's not bad at all. It takes longer and you'll end up with 300 pots in your backyard but you'll know first hand about your trees and what can be done with them. Bonsai is a "learning experience" . Even though alot of these trees won't amount to anything in the long run you are gaining knowledge by keeping and growing them.
.........Or, if you have the money you can buy good trunks and nebari and only concern yourself with pinching.
If you are like me, you'll find your fun in the growing of bonsai not in owning them.
Tony