The lead engineer for one of the top post facilities here in town told me once that digital tapes are good for up to 100 passes. There was no reason to use them just once.
I had 6 episodes of Good Eats that needed a change after we finished the masters and I was going to lay them off onto new tape stock. he told me that was a waste of money and I could safely use the tapes (DVCPro HD) for at least 100 passes with a clean VTR. Needless to say we simply mastered over the original cuts, sent them off and as I have not heard anything about those episodes in 4 years I guess QC had no issues with them.
Walter Biscardi, Jr.
Editor, Colorist, Director, Writer, Consultant, Author. HD Post and Production Biscardi Creative Media