I think mine was about a week. How can you afford to tie up an imager for a month, unless you have multiple or so very little business (which I doubt)? ,,, or can stop the job when the imager is needed for another job then restart it when it would otherwise be dormant. Personally, I find it difficult to sleep while an imaging job is running all night.
Right now i've got an 8Gb flash drive that I've been re-reading bad NAND blocks for about three weeks. Despite only having about 50Mb of unread blocks left, nearly every file is affected by a few bad sectors still.
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