Arbitrary distance units. This fixed-count model explains an experimental idea; it is not a simulation fitted to desert ants.
Rule: count = outward distance ÷ outward stride. Repeat that count on return. Return distance = count × return stride. Fractional strides are permitted because this is a continuous arithmetic idealization.
Try equal strides, then change only the return stride. Change both to the same larger value. Does having a longer stride alone create an error?
The model omits direction, visual cues, terrain, stride variability and learning. Real navigation combines more information.