Thesis
The same part can require a genuinely different, equally valid process plan in different factories, because machines, tooling, setup practice, and process capability differ from shop to shop. A route recommendation that ignores factory context is not more objective than one that accounts for it — it is simply answering a narrower, less useful question.
A concrete case
Take a part with a keyway. One shop, with a broaching press in regular use, cuts the keyway by broaching: fast, clean, a well-understood process for that shop's tooling and operators. A second shop, without a broaching press but with strong wire EDM capability, cuts the same keyway by wire EDM instead: slower per part, but well within that shop's existing process knowledge, tooling inventory, and quality history.
Neither shop is doing it wrong. Neither route is a fallback for lacking the "proper" equipment. Both are legitimate, defensible manufacturing plans for the same drawing, and the reason they differ has nothing to do with the part — it is entirely a property of what each factory actually has and knows how to run well.
Why this is not a new observation dressed up as one
This isn't a novel claim invented for this article. Alternative and flexible process planning — the idea that a single part can have multiple valid, executable manufacturing plans rather than one correct one — is an established area of manufacturing research. Nonaka et al. describe an automated process-planning method that, starting from part geometry and a description of available machining resources, generates a "portfolio of executable process plans" for a single part, with the explicit goal of balancing load across the machines in a workshop.1 Their research question is about efficiently using the resources inside one workshop with multiple machines — not, directly, about why two entirely different factories would land on different plans. But the underlying finding generalises naturally: if the geometry and requirements of a single part are compatible with more than one executable process plan even inside one shop's own resource set, the same holds, more strongly, once tooling, machine inventory, operator experience and process history differ between shops rather than only between machines in the same one. That extension from "multiple valid plans within a workshop" to "multiple valid plans across workshops" is this article's own synthesis, not a claim made by the cited research itself.
A second case, driven by a different variable
The keyway example is driven by tooling and process capability. A second, equally common case is driven by tolerance and inspection capability instead. Consider a part with a tight positional tolerance between two bores. One shop machines both bores in a single setup on a 5-axis machining centre, holding the tolerance directly through fixturing accuracy and a single coordinate system — a route that requires that specific machine class to be available and proven capable at that tolerance. A second shop, without a 5-axis machine but with a strong CMM-based inspection and fixturing discipline, machines the bores across two setups on a 3-axis machine and holds the positional tolerance through a jig-bored fixture and verified, repeatable re-indexing — a route that trades machine simplicity for a more demanding fixturing and inspection regime.
Both routes can genuinely hold the tolerance. Neither is inherently more correct. The first assumes a specific, expensive machine class is available and reduces the setup-count risk that the second route accepts and manages through fixturing and inspection instead. Which one a specific shop should choose depends on what it already owns, what its fixturing and inspection practice can reliably deliver, and what its own quality history says about multi-setup positional tolerance work — none of which is a property of the drawing.
What the obvious answer gets wrong
The instinct is to assume one of the two routes above must actually be better, and that a sufficiently capable analysis would reveal which. That instinct treats "better" as a property of the route in isolation. In practice, "better" is only meaningful relative to a specific factory's actual constraints: what machines it has paid for and staffed, what tooling it already owns, what its operators have deep, tacit experience running, and what its own quality history says about a given process. A route that is objectively better for a shop with a broaching press already in use can be a worse choice — slower to implement, riskier, more expensive in practice — for a shop that would need to acquire that capability from nothing.
The practical consequence for manufacturing software
Any system that proposes a manufacturing route implicitly answers a scope question, whether or not it says so out loud: is this the best route for a generic, idealised shop, or the best route for this shop, with its specific machines, tooling and history? A recommendation that silently assumes the first, while being consumed by someone who needs the second, will look confident and be quietly wrong in exactly the cases where shop-specific constraints matter most — which is most of the time, for anything beyond the most generic commodity part.
This is the direct, practical reason "the answer depends on the factory" is not a hedge or a disclaimer. It is a structural property of the problem. A route recommendation that doesn't ask about factory context isn't a more rigorous answer — it's an answer to a different, less useful question that happens to look the same on the page.
Subduxion's interpretation
This is Subduxion's own research framing, not an established industry consensus: representing factory context — the specific machines, tooling inventory, and process history available to a specific shop — as a first-class input to route reasoning, not an afterthought layered on top of a generic recommendation. That framing is a current research direction, reflected in how Subduxion approaches representing a factory's own capability, not a claim that this is already a solved, shipped capability for every process and every shop today.