I know that. I mean how many tracks does each channel have before it rotates. like say, the "rock" channel is on, how many tracks does that have?
i don't think there's a way of knowing without watching them all and counting. the on-demand portion would just give you access to the entire catalog (i assume), so I'm not sure how you'd figure out how many are on at any given time. i'm sure we'll know very soon if it feels like songs are repeating too often (or not enough)