I don't think its the disk passes thats the issue I think its the reading and writing to and from the disk.
I use Eraser myself and its set to use Pseudorandom over writing multiple times. Now the platters spin what... 7200 rpm on modern drives. The head will pass the same spot more than 9 times a second!
I personally wouldn't worry about it if its just the one shred. What I will advise against however is using a disk repeatedly for starting up and shutting down Virtual Machines. I've learnt from that mistake. Running 2 or 3 OS's on old drives at the same time doesn't do them a lot of good. I've had numerous drives go a bit ... weird after a few months of it. What I would suggest for VMs now is simply to suspend the machine and then resume it again when needed which is what I've been doing now for a few months and I'm glad to say the current disks they're on haven't suffered as quickly as the previous victims.
I know that has nothing to do with shredding but its also a big read/write operator. It took months of continual usage of VMs starting up and shutting down to do the disks over so one shred should be fine. There isn't really a way to tell when a disk will die but so far all 4 of the ones I've had go bad have started to show signs of being slower than normal to read and write. Listening to MP3s from them was the first indication that the drive couldn't transfer enough data. Forget the software tests - all mine said the drives were fine! Days later after my most recent went on a go slow it totally died despite software reports saying it was in good health. That particular drive now does absolutely nothing. The other 3 still have occassional use for backing up onto but they're rarely used as they can't handle the workload.
I suppose you could think of it like a car. Treat it with a bit iof respect and it will serve you for years. Thrash it around like a racing car and rev the hell out of the engine and its gonna let you down sometime soon.
I need a new signature... i'm bored of the old one!
