Re: Cribs from touch
There are actually two types of "personalization." The first has been mentioned a couple of times, the habits of certain individuals to compose messages the same way. I especially enjoyed the "Nothing to report" standard message as being a good crib.
The other type of personalization was the Morse code sending itself. (Being an old ham radio operator, I speak from experience.) Every Morse code operator has his, or her, own rhythm. The weight (length) of the dots and dashes vary from person to person. With practice the interceptor learns to recognize the rhythm, sometimes called "the fist," of certain operators. Joe's code sending definitely sounds different than Mike's, etc. Then, couple Joe as the guy who always sent Jim's messages, and you have valuable meta data on beginning to decode messages.