ORIGINAL: Carewolf
I tested this by using the editor to place a debris field and remove all but one ship. Added (editor again) two construction ships, the first with one of each plant and the second with two of each plant. Noted start and completion dates of with each ship. The repair time was identical.
Very interesting, but maybe this is specific to derelict ships. Have you tried the same with building bases and repairing normal ships?
Repeated the test, but timing building a mining station. Again, no difference. Multiple construction yards and/or multiple manufacturing plants on a construction ship gives no benefit.
Here's my interpretation:
Each construction yard can work on one project at a time. In the case of a port, that would mean that multiple construction yards might be building or repairing several ships (one each) at the same time. However, a construction ship can only have one project - build something or repair something.
For the project of each construction yard, the items to be built are in a queue.
a. Each item in the queue requires a specific manufacturing plant - weapons, energy or tech.
b. When the item is being worked on by the construction yard, it adds the item to the manufacturing queue.
c. Manufacturing queue selects an appropriate manufacturing plant type and determines its completion time.
d. If no manufacturing plants of the appropriate type are available, the queue waits till one is available.
e. If required resource is not available, the manufacturing plant waits till the resource is available.
f. When the item is finished by the manufacturing plant, it is moved from the manufacturing queue back to the appropriate construction yard. Construction yard then returns to step b fill the project is complete.
So, in a construction ship, you can only benefit from a single construction yard and one of each type of manufacturing plant. In the case of a space port, the maximum speed you can construct is one plant of each type per construction yard, to prevent queue waiting at d.
This would explain why having no chromium, for example, causes ALL construction at a port to stop - all construction yards are stuck at e.
Or that's my interpretation. Personally, I'd check to make sure resources are available at step c, and if lacking, move the item to the back of the queue. Repeat till all items fail. If all items fail, and if it's a port, rinse & repeat for next queued project. That way, the port wouldn't stall for need of a particular resource, but would do what it could (eg: repairing ships which do not require chromium from above). But that's not how Elliot seems to have done it.