I work in manufacturing as well, and what strikes me is about this is that Marx seems to have talked to actual, real business owners about how they think about and account of the running costs of doing business. Marx is of course presenting as a model built from first principles, but it's clear that it does actually fit with the way capitalists actually do capitalism.

Yeah, it really struck me in volume 1 that the notion of socially necessary labor time maps really well onto the Lean manufacturing notions of value-added and non-value added labor (Marx's explanation is of course more flexible and has more explanatory power, thus clearing up some of the misconceptions that are likely to arise, but there is clearly a common idea-seed.) Similarly many of the principles of the social productive powers of labor arising from co-operation. Here in the beginning of Volume II we even begin to understand the Lean obsession with inventory minimization and just-in-time manufacturing, which initially appears to many of us on the left as ridiculous if not outright delusional, as stemming from capital's drive towards constant, unimpeded progress of its various forms through the circuit as the means of generating as much return on investment as quickly as possible.