1. Data transfer throughout the 8″ floppy product life never much exceeded a 2400 BAUD modem, if you can believe that. So loading 15,000 of them could average several minutes each. Estimating 4 minutes to handle and read each one, I figured installing Win10 would be a full-time job for about six months (well over 1,000 hours).
Note A: The 4 minutes per disk figure accommodates occasionally knocking over a pile of several hundred disks onto the floor, and subsequent time spent gathering them up and restoring their proper sequence. We assume this would happen at least a few times per day during the 6 months.
Note B: The 4 minutes might not accommodate unreadable or missing disks. The failure rate for 8″ floppies was far greater than 1 in 15,000, and Microsoft, in its infancy, would surely have botched a significant number of shipments. Given MS customer service in that era, obtaining a damaged or missing floppy could pause the installation process for several more months.
2. One seriously unfortunate detail in the 8″ floppy Win10 install scenario is that the install is 4 gigabytes (four billion bytes), but of the hand-full of 8″ floppy-based PCs of that era with hard drives, virtually none was larger than 10 megabytes. So before loading the 15,625 floppies, you’d have to first install 400 hard drives. Since the computer could only recognize a maximum of 14 hard drives & 2 floppies, you’d also have to rewrite the operating system, or at least the BIOS. Installing 400 drives might take a couple of weeks, plus ordering them and waiting for them to arrive, but we could assume that was done before ordering Windows 10. Rewriting the BIOS might take anywhere from a few days to a few months, depending on the user’s familiarity with 8080 assembler language. It took me about a month of spare time to write a BIOS driver for a Cipher 9-track tape drive for CP/M, but that was a lot easier than writing drivers for Windows.
In conclusion, I’d say the whole installation process should be doable in something under 1 year.