For me it's often about adjusting the reserve.
Or sometimes I'll put a domain up and won't promote that it's up for auction to potential buyers and just look for a quick sale and if doesn't get enough interest I might consider putting it up for auction again and contacting potential buyers about the listing.
Or maybe a domain is coming up for renewal that you previously placed on the AMA and now you are willing to sell it at no reserve whereas you weren't previously.
The point is there are reasons to put a domain up for auction twice, though I don't know if I'd ever put a domain up for auction 5 times in 90 days, but I guess there isn't much harm in doing that either.