 It is completely possible that the Gravedigger has been a sexton for 30 years, but has not been digging graves for that entire time.This could be another example of the character's very round-about way of speaking.However, this reading has the disadvantage that in the Folio the length of time Yorick has been in the ground is said to be twenty-three years, meaning that he had been dead seven years by the time Hamlet was born.