The Time of Birth on Baptismal Certificates for San Miguel

Recently I started my Familytree Maker cleanup of my Alviso/Bejar genealogy trees. I am adding a few things I did not add originally. One is the time of birth. Oddly, many of the times are 3 pm, and I know this many children could not have been born at 3 pm. Was this just a catch all time in case the exact time was not known or possibly they just guessed not having clocks? Some also have other times such as 12 noon or 11 o'clock at night, so I am not sure why 3 pm was so popular. Has any one else noticed this?

Maureen Bejar