I think ,in my case at least...it boils down to "time out of ground", and whether it was "dipped, soaked, or just thrown in a box".
I seem to get the "fastest starts" from those that are dug, and thrown into the box, and mailed, all the same day. Even in "hot" conditions, and with an "unventilated box", they seem to do the best. Those that have been soaked in bleach solution, dried for a few days, and then mailed, seem to be the ones that take the longest to start growth....and they also seem to be the ones that "lose" all there original leaves, and then "start over"
The amount of "root" left on the rhizomes , except for providing an anchor for the plant, doesn't seem to affect the time it takes for new growth to start, but, I've found that a good soaking in "plain water" (or maybe with a bit of Miracle Grow added) really speeds up the process.....whether they are 'fresh dug",OR dried out.
There are so many variables involved, that , again, it boils down to finding a system that works for you, and the "experience" to decide which ones get a long soak, or need potted for a while, or whatever special care you think they need.
I suppose, if a person wanted to play around a bit, you could dig a clump, separate some similar sized rhizomes, and do some experimenting . Plant some in 3 days, some in a week, soak some in bleach water, "dip" some, plant some in the ground, and put some in pots, in a shaded area. But, really, they ALL seem to grow...or at least the vast majority of them. Depending on what stage of growth they were in when dug probably has more to do with "if they bloom the next year", or take two years to do it." Late dug" rhizomes, of course, are going to be larger...but, more to the point, they will have already formed the "starts" (there is a 'technical term for them, but I can't remember it
)of the next crop of stalks, while "early dug" rhizomes may be "interrupted".....and take an extra year of growth, in order to bloom.
