Primary burial was not always the final stage. A body might first rest in a niche or on another surface within the tomb. After decomposition, the bones could be collected and moved to a smaller permanent location.
This practice freed the original burial space for later use and kept the remains within the family tomb.
Secondary burial became particularly prominent among Jews in Judea during the late Second Temple period. Bone gathering and ossuary burial are therefore characteristic features of the archaeological world surrounding the New Testament.
Secondary burial meant that relatives returned to the tomb well after the funeral. Death therefore involved more than a single visit to the burial place.
Excavated tombs contain gathered bones, ossuaries, reused burial niches, and other direct evidence for multi-stage burial. Jericho and Jerusalem provide especially important examples.
Jewish sources refer to the gathering of bones as a recognized practice. Later rabbinic discussions preserve memories and regulations concerning this second stage of burial.
The older biblical phrase "gathered to his people" should not simply be equated with the later archaeological practice of ossilegium. Secondary bone gathering was a specific development of later Jewish burial custom.
The Gospel burial narratives describe the initial burial of Jesus, not a later gathering of his bones. The resurrection proclamation therefore interrupts what might otherwise have become an ordinary continuing burial process.
Secondary burial and bone gathering are firmly established by archaeological evidence from the late Second Temple period.
The practice was common in particular regions and social settings but should not be assumed for every Jewish burial throughout Palestine.
Understanding two-stage burial explains why tombs could contain both places for newly dead bodies and boxes holding the bones of earlier family members.