Great article that provides information on what the egg song truly means. It should be noted that not all roosters will accompany a hen when she is laying her egg-mine will make the egg song reply to the hen, but he will not escort her anywhere and he will ignore her while she is laying. It is only when she gets off the nesting box and makes her egg song again that my rooster pays attention, and he goes over to wing-dance at her, often not trying to breed. Also, one of my pullets will ignore my cockerel's attempt at finding her nesting sites, and she will choose herself and run away from him if he gets close. Every chicken is an individual and does not follow every standard set for them.
Edit: I also should note that another one of my pullets, a Rhode Island Red Bantam, never does an egg song and instead makes a chittering noise while laying her egg, and screams occasionally because I am sure laying an egg would be painful. The cockerel in her pen also ignores her and does not sit with her on the nest. Meanwhile, the Silver Sebright pullet in the same pen does make an egg song and the cockerel will accompany her. As I mentioned before, every chicken has their individual preferences, so I assume that my Rhode Island Red Bantam prefers if the cockerel does not sit with her for whatever reason.
Edit: I also should note that another one of my pullets, a Rhode Island Red Bantam, never does an egg song and instead makes a chittering noise while laying her egg, and screams occasionally because I am sure laying an egg would be painful. The cockerel in her pen also ignores her and does not sit with her on the nest. Meanwhile, the Silver Sebright pullet in the same pen does make an egg song and the cockerel will accompany her. As I mentioned before, every chicken has their individual preferences, so I assume that my Rhode Island Red Bantam prefers if the cockerel does not sit with her for whatever reason.