I have the startup setting for the Minimum Upgrade Time as 5s, yet I am capable of upgrading items in the Post Processor and Calibrator successfully in less than 5s. For example, storage chest post processing's recipe takes 6 seconds. In an epic post processor, it takes 6/1.9 seconds, and even with 2 epic speed 3 modules, it takes 6/5.51 seconds yet successfully completes. When I try to Upgrade it even further, after a successful upgrade to rare quality, through a reinforcer at the same crafting speed, it fails the upgrade and spits out a rare chest. I adjusted the quality inputs to the appropriate level below desired output for quality.
Even solar panel reinforcement works under the same conditions with a 5.5s (and the same adjustments of 5.5/1.9 and 5.5/5.51) crafting time. I have no clue what the issue may be and I would rather not have to restart to increase the minimum upgrade time.