It won't damage the cartridge, or the Cardas LP. I've left slow-to-break in cartridges on those tracks for many hours. How long is needed depends on the cartridge. An arbitrary "rule" like one hour is just that - arbitrary.
Important: clean the stylus thoroughly after each session (Magic Eraser + brush).
All that said, unless your new Blackbird sounds bad, why not just play music and enjoy/learn from the changes as it settles in? The only time I use the Cardas break-in tracks is for cartridges that sound really bad when new (names withheld to protect the guilty).
The frequency sweep tracks are another matter. I run my cartridge over them once every week or two. Helps sweep out the cobwebs a bit.
Important: clean the stylus thoroughly after each session (Magic Eraser + brush).
All that said, unless your new Blackbird sounds bad, why not just play music and enjoy/learn from the changes as it settles in? The only time I use the Cardas break-in tracks is for cartridges that sound really bad when new (names withheld to protect the guilty).
The frequency sweep tracks are another matter. I run my cartridge over them once every week or two. Helps sweep out the cobwebs a bit.