But this sounds to me as the sort of knot could be different (a diffent metaphorical usage). When a tree grows, and branches leave the trunk, the wood - when sawn up, shows points where the grain gets tighter and tighter and forms a tough and unmanageable piece of wood called a 'knot'. Knots in wood are undesireable structurallly (the wood is tough, but where it meets softer wood there is a weakness.) Rarely, knnots can be regarded as attractive (don't ask me why: judge for yourself: http://www.jastimber.co.uk/images/pi...ictorian_4.jpg) - hence the popularity of 'knotty pine'.
The quote could be about the development of a new recruit, training whom was not perfectly smooth.
PS Etymological tangent, following up your point about 'untying a knot' meaning 'finding a solution'. English speakers, when discussing literature, often borrow the French dénouement to refer to the end of a novel,. The French for 'knot' is nœud so dénouement means just that. We turn the metaphor on its head when we talk about 'tying up loose ends'.
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