Construction factories seem to produce and consume ship/pdc parts and certain facilities at the wrong rate once the construction value gets high enough. I have noticed this with PDC parts(too few produced), terraforming modules + terraforming OHs(500 parts produced, 10-50 part OHs built, 450 parts left over), and with naval complexes(ordering two only produces one yard). I have 3007 construction factories producing 119807.9 BP per year, and each construction order occupied a single slot rather than multiple slots.