I got the impression that for the second to last collection, we needed to split the characters to send them to different buildings, by using the trick where you hide the primary building, let a few characters go to the secondary building, then restore the primary building for the rest of the pack. That could have allowed one extra 5 (at least) to already be in your tally when you begin collection of the last 200. That's how i got my newtube building already.
That said, i do have the new aliens collecting at the premium rate. If you didn't have them you likely couldn't have collected at the rate i did.