Folks tend to develop distinctive styles for their signatures, which vary from their normal cursive style.
E.g., check out this letter, dated Thursday morng, 2 Octb. 1783, from John Hancock to his wife Dolly:
Transcript to be found here
Compare the J in "Do write me how Johnny is & all of them." (most of the way down in the first paragraph) and the J in "A Large Speaking Trumpet for Johnny" (tail end of the list of "I have sent you") with the J in the signature.