Time to bring up the creator of Babylon 5, and sometime writer on Murder She Wrote, responding to people saying "We already figured this out", once again. Paraphrasing with a bit of quoting;
If no one figures it out, you're doing your job wrong.
If everyone figures it out, you're doing your job wrong.
Of COURSE some people figure it out, they're paying attention.
If you're doing your job right, and laying out the clues, a certain number of people HAVE to figure it out.
"The best case scenario is a bell-shaped curve. Some don't have a clue what's coming, some manage to figure it out, and the majority have a kind of vague sense where it's going, but there are still surprises along the way. If the bell-curve shifts one direction or the other, then you're in trouble."