As an example, in my tree are a couple Robert Sherlicor and Esther Moorcroft. They got married in 1731 and died in 1802 and 1786 respectively. Their last child was born in 1747.
A book called "The Annals of Southport and District" states that "September. Died, aged 99, Esther Sherlocker.
Sixteen years later (April 16th, 1802) her husband was buried, aged 101. Thus their united ages covered two centuries."
This would have made Esther about 44 when she got married, and 60 when her last child was born! There are possible baptisms for her in 1700 and 1704 so I don't believe the Annals.
Not always so easy to check, though.