Incorrect Assumptions

For best min/maxing it is recommended to juggle Engineers around for an average skill level of 450 for the small Workshops and 850-900 for the Advanced Workshops. As the random factor (time for research/manufacturing) of the previous 2 games has not been implemented in Apocalypse, you will always get the full skill level progress for each ingame hour passed, while the total skill level required for the project will also always stay the same. Therefore the highest "realistic" even skill number (450 / 850 /900) per Workshop will allow for the fastest manufacturing of items/craft (as most projects have even total Skill Requirement numbers). The difference between 449 and 450 can already be 1 - 5 hours, depending on the project.

Wrong.

Every single skill point closer to the perfect 1000 will decrease the time taken.

Project complete screen only appears at the start of a new hour. If your project takes even one more minute in the new hour, you lose 59minutes because ..."start of a new hour"!
Best scenario would be to time a project so it finished exactly 1minute before the new hour or (prefered):
Start a project to last many ~~days~~ so that losing 1hour of time at the end becomes insignificant.

eg: losing 1hour of a 96hour total time production run is almost irrelevant, but losing 59minutes every 1hr+1min project run is unacceptable waste.