Was that just the scan time, or did it include set-up time? Put another way, how much time per image goes into setting scanning options, previewing, determining whether to use ICE, etc.?
The time was from when you click the scan button until the scan is complete and appears on your monitor within the Nikon app or within PS if you have chosen to import it directly.
I never adjust the scan frame on an individula basis. I establish a window frame which is just larger than the slide. Any black border which is capture I crop in PS before saving the file or leave it and crop when I go back to PP the image. Same with the negative strips. All four or 6 frames get captured with some of the outside border.