This may not be exactly what you are asking about. But I have felt the need to share this for a while, and thought this might be an opportune time. Many bonsai growers, even professionals, grow what I call "baseball bats". By that I mean ramrod straight material with very little taper. Anyone can do that. The trick to growing good trunks is to wire them BEFORE you put them in the ground. My method of growing stock is below.
Pre-wire cutting material. After new growth extends in the spring, but before it lignifies, wire material you want to take cuttings of. Make extreme bends, these will be softened by growth later. Strike cuttings in late spring or early summer, after the branches have lignified (or if your prefer, after the leaves have "hardened off"
). The next spring, plant these cuttings in a shallow pot, making sure that the trunks are not emerging perpendicular to the soil line. The plants won't grow much in the shallow pot, but you will get a good start on the nebari and you will have lots of low buds/branches to work with in the future. Be sure to wire the trunk extension and any long branches you might get. You never know when an alternate trunk line might develop. The next year, pot the plant in a deep container, like a nursery can, and feed heavily. You're looking to develop a strong root system. If the plant is growing strongly, you can plant it in the ground the following spring, oR move it to a lager pot.
Yes, this takes more time that plopping a seedling or cutting in the ground. But then you're not growing baseball bats.