There are various review threads that don't have a poll. Grafting polls onto them is possible, but inconvenient: According to Rosalind she can't add polls to existing threads directly, so to add one to the new The Rings of Time thread I had to open a second, poll-equipped thread, which she then merged into the older one. Now I'm willing to do this work for other threads, but it means a new reply (due to the merge) pulling them back to the front, which might be annoying, especially if done all at once. Maybe one per week? How do you all feel about this? And the mods would need to support it too, of course.
I don't mind, as long as it's not done all at once
<research scientist hat>
if you add polls to old review threads now:
-- you won't have the same people who posted in those threads voting, so you don't get a good representation of the reviews.
-- what people vote a year (for example) after they've read a book would statistically be different from what they would vote straight after they've read a book. so the ratings would mean different things.
so, I would discourage adding polls to old threads, but rather have new polls for them, and have the ratings in a different table.
</research scientist hat>