Cardas Frequency Sweep and Burn-In Record ?

On the Cardas site he speaks about using the record to break in a cartridge. He says the amount of break in varies but he recommends an hour? So does this mean if I use this track to break in a cart I cant leave it in the groove for extended periods of time? Do I risk damaging the cart if I do so? I am trying to break in a Sumiko Blackbird
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.
Tracks 2a, b, and c (I think) are great for reviving a cartridge that may be broken in but has not been used for several weeks.