chewylsb said: I find it very hard to believe that you didn't see the mythic X spells as a cycle. You don't do mythic instants/sorceries very often at all, they take up literally 20% of the mythics in the set, and they each correspond to a guild. To me its just impossible to not see the pattern there, especially for a set you've been working on for months.
It is much easier to see patterns with a completed set. Remember that sets in design and development are fluid. The set could have had two mythic X spells forever and one was added at the last minute. It would be harder to catch that if the previous two just felt like cards that were already there.