The 15 Song Album collection:

Yes, the "rules" if you want to call them that are:
1. No more than one per day. Be reasonable don't post one at 11:30 pm and another at 12:15 am. At least have a sleep between your posts.
2. No more than two per list. Again, if it is really dragging on, then as long as the list starter agrees, maybe one more.
Other than that, it's up to the starter to control how tightly we adhere to the rules. I think we might have been a little loose on the 'beach' list for example but that's up to the starter.