Were the ox and the fattened animal sacrificed only at the beginning of the journey (after six steps) or throughout the journey (every six steps)?
Most likely the ox and the fattened animal were sacrificed only at the beginning of the ark’s journey to Jerusalem. Symbolically, the six steps suggest some kind of connection to Sabbath rest (see Genesis 1:1–2:3) and consecration for the entire journey.1
13 And when those who bore the ark of the LORD had gone six steps, he sacrificed an ox and a fattened animal.