Relliker

The only benefit I can find for merging is when building cargo bays. According to the specs for cargo blocks, there is an unusable wall thickness of 2.5m for each individual block. Merging tells the game it is one block instead of multiple blocks. ( source cited at bottom ) I found this has giant net effects when building factories. I tried this with other blocks like hanger, engine, and crew quarters to no avail If anyone knows of any please let me know. cargo bay source

I am not sure how you are arriving at your calculation of hours. I am down to a production time of 1 minute and 14 seconds per fighter. I know you can craft some fighters with a required production in the millions. I would assume this is your issue. Also, if you have multiple concurrent fighters in production it will greatly increase the time each fighter takes to build. Do you have any of the production specs for your ship and the fighters you are trying to produce?