Just a guess, but "12" is probably a number that is connected to bitcoin's value. Just like the value of free roll. Spins hold no value to me either.
Your guess is right. As I already said in
my previous post, WOF rewards are adjusted based on bitcoin price.
I just played a WOF spin I received through a promotional email and the prizes were 13 satoshi, 13 reward points and 13 lottery tickets.