Leaving the wire in when developing the trunk is a technique used to increase girth in a relatively short time. It does work - but I would caution that I think it takes technique and skill to apply the wire so that as the tree grows over it, it doesn't create reverse taper AND it looks natural. The good examples I have seen I think have the wire put on in a more random twist than your regular wiring application, so that the tree doesn't end up with a scar/growth that looks like a candy cane spiralling up it. I have seen plenty of examples that make me think twice about doing it ... I just don't know how to apply the wire in the best way to guarantee a natural result with no reverse taper. Some pics below with what I am talking about ...
JBP - wire scars.jpg
JBP - wire scars 2.jpg
... couldn't find one with the candy cane, but hopefully you get what I am trying to say. Looking at your long term goal - I don't think it was developed with this technique (but doesn't mean you couldn't!)
As for developing the nebari - 100% agree that the more time you put into that in the early stages the less drama you will have in the future, and the better tree you will have down the track. Definitely agree with the point about keeping your nebari buried as it develops too, don't expose it too early. That's a trap for young players that I have been guilty of in the past. Nebari is one of the things that really elevates a bonsai when it is en pointe, so I would encourage you to keep it at the top of your agenda.
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