Some people believe that the act of laying eggs is equivalent to pregnancy in humans. It isn't so. In chickens the act of sitting is the human equivalency of pregnancy. A hen laying an egg is only equivalent to a human woman ovulating.
When a hens goes broody many changes take place in her body, just like changes takes place in a pregnant woman's' body. I'll allow the mothers out there to enumerate the ways that being pregnant are uncomfortable, then through in the following.
I want you mothers out there to ponder being pregnant and having to sit quietly in only one position for 3 or 4 days at a time.
Think about not eating or drinking for 3 or 4 days at a time.
Think about being pregnant and not seeing or feeling the Sun on you face for 3 or 4 days at a time.
What do you ladies think it is like to not be able to have a bathroom break for 3 or 4 days in a row.
And if your chickens' premises has mites, and most do, try to imagine sitting in one spot day and night for 96 hours at a time and let bed bugs gnaw on your hide and feast on your blood!
For a hen to lay eggs she MUST be in good health. Allowing hens to sit, and sit, and sit, for no reason is cruel in the extreme, and it only damages your hens future health and makes them more susceptible to contracting deadly diseases.