In a student's first week in MATH 1111, they are asked a question about whether the ability to decrypt a code depends on intuition, creativity, or luck. At least in this year's class, the majority of students picked either intuition or creativity for various reasons. None of us anticipated that luck would be the key to any of this.
I have quickly learned that luck is the key to breaking any cipher, and that is the very reason why in practice, breaking cipher texts are so much harder than they seem. The common tests we use such as frequency analysis and the Kasiski test are effective in giving us hints and clues, but they fail to give the cryptanalyst any concrete or definitive pieces to move forward with. The hints and clues we receive lead us in the right path, but we still are forced to test and guess our way towards the answer. There is only so much that intuition that take us in terms of completely cracking the code. This is why there are codes and ciphers in the world today that are deemed "unbreakable", no matter how much time the world's best mathematicians spend on them, let alone a group of first-year college students.
Because the fundamental purpose of a cipher is to hide the message from any in the way of the message's delivery, its natural intention is to make sure it is as close to uncrackable as humanly possible. This inherently means that there will be intended twists to make deciphering even more difficult.