Weep holes in masonry walls serve an important purpose by allowing moisture to drain out of the cavity behind the wall. They help prevent water from accumulating and causing damage to the building. Weep holes should be installed at the base of walls and around openings like windows at regular intervals, with a recommended spacing of every 33 inches. While some homes were built without weep holes and have not experienced issues, their inclusion is considered a best practice and is required by most building codes. The absence of functioning weep holes can eventually lead to problems like rust, wood rot, or insect damage if water is unable to drain properly.