Well, no, you may be right re the 12 hours. It is still 12 hours. I was collecting only once a day when I only had one, and the icon would pop up at the 12 hour mark. Now I Collect every 12 hours, and the icon pops up at the collection time which happens to be 12 hours.

I was thinking it was like the coin habitats, which seems to be a percentage. The 12 hours makes sense, but I didn't pay any attention as I was levelling them up to determine if there was any differences.