What if my handwriting keeps changing?
There are also many who claim that their writing is changeable; that they never write twice alike. This is true to a certain limited extent.
Probably no one can produce three specimens of his own signature that are absolute facsimiles. But the differences are purely superficial.
The style of handwriting varies no more from day to day than does the outward appearance of the individual. A change of emotion will produce a corresponding change in the expression of the face. A different style of hat, a change in the mode of wearing the hair, the shaving off of a beard or any alteration of a like character will produce its effect, but the individuality of the person is not affected thereby. In a similar manner, our penmanship is superficially modified by our feelings, our physical condition, by the kind of ink we use, the style of pen, the kind of paper, etc., but its individuality remains unaltered.
Source: Graphology or How to Read Character from Handwriting BY SIMON ARKE American Institute of Graphology 305 Lenman Building Washington, D. C. 1903