The easy answer to the question "How to repair book spine with duct tape?" is that you just never, and I mean it, never use duct tape and most of the other types of tape on books and documents of at least some value.
This specimen of convolute binding really put into a quandary. This volume included a year's worth of Russian magazines Printing Art ("Печатное искусство".) And it had one of the pages from the first issue cut out.
Another find at a thrift store. I love everything about this Bible. The cover pattern is amazing. How the book feels in your hands. And I suppose the repairs were done by the previous owner after long and heavy use.