I'm pretty sure they didn't. The substitution message always said no more the 50% of the time on the world was allowed, but their coding was wrong and it was never implemented, until now on new worlds.
30 days at time also seems reasonable.
The problem many have is with the concept of changing the 'rules' (or implementing them) after such a long time. Where it is a bug fix then, I agree, it should be implemented on all worlds. Where it is a modification such as when they introduced malus and the forgotten attacks they rightly decided not to patch existing worlds with these changes. (It could have been done for technical reasons but it doesn't matter why they didn't implement the changes on old worlds.)