I can never tell if this is a bug or a WAD, but I keep noticing it.
The Construction Queue does not seem to use excess construction on items in the queue if the time increment is greater than that needed to finish the item currently being worked on. This does not match up with the research queue, which seems to calculate the amount of research generated, and then applies it to the queue.
In case that was too opaque, let me try an example. Assume I generate 1000 CP and 1000 RP in a 30-day increment. I have all of my construction currently going toward a research facility which needs 200 more CP; after that, I have a Sector Command queued up. On the research side, I have an engine needing 200 more RP, with nifty new laser tech queued up after that.
If I increment 30 days, the end results seems to be that while my engine tech has finished and 800 RP has been applied to the laser tech, and my research facility has been finished, but the excess CPs disappeared into the ether; no work has been applied to the Sector Command.