Pronouns refer to a noun; in a sentence, it should always be clear as to which noun the pronoun is modifying. If the reader has to spend time guessing which pronoun refers to which noun, they may give up reading.
The mother called the daughter back to clean up her mess.
Did the daughter not do her dishes? Was the mother a slob who thought her daughter should clean up after her? Which female does the pronoun her refer to?
When the daughter made a mess, the mother called her back to clean it up.
Even with two pronouns, the references in this sentence are clear.
Buddy put a bullet in his gun and shot it.
Did Buddy shoot the gun or the bullet?
Whenever Mark feeds the baby, he eats too much.