Reality Check...
1. The Mini-DV tapes made today can be re-used, there's absolutely no doubt about it. How many times? Depends on the quality and thickness of the original tape stock and how they have been stored.
• 60 minute tapes are somewhat thicker, heavier in design (less stretching and folding) and will last longer. A 30 minute tape is the same mil thickness, so no savings there.
• Tapes that are "stretched" or fast-forwarded and rewound will likely work better the first time through the camera
• Tapes that are properly stored in a cool, dry location and shielded from dust, sand and extremes of hot and cold will recycle better
2. Typically, "drop out" is a greater function of camera heads that have not been cleaned or have been cleaned improperly, leaving chemicals or scarring on the heads themselves. That's right...it usually isn't the tape that causes the drop out, it's the camera heads!
I wouldn't hesitate to recycle a camera tape 3 times if my heads are clean and the good quality tape has been properly cared for in the field and in storage.
In real world use, those DV tapes are my archive backup. But there are times that I have recycled them if entire tapes have been digitized and the master material is safely stored on hard drives.