For what it's worth, I work in industrial controls. More or less all of the machines we design are one-offs so engineering and labor time dominates the cost of projects vs. materials.

Additionally, unplanned downtime is extremely expensive. If a machine breaks down and a replacement part isn't on the shelf, getting that part fast is much more important than saving a few dollars. Same goes for if we end up with a bunch of guys waiting around for a part to get installed.