> that one should never change the letterspacing of the lowercase letters But with the microtype package it is acceptable to slightly expand or contract the le

> that one should never change the letterspacing of the lowercase letters But with the microtype package it is acceptable to slightly expand or contract the letters to avoid hyphenation. Typically the limit is set to around 0.025em. Anecdotally if you are applying letterspacing to uppercase letters, 0.025em is also a good default value to use.