When steel helmets were first issued to the British troops they were handed over from the unit leaving the front lines to the releiving unit. This was until the production rate met the demand for them to be personal issue.
The new German helmets were first handed out at Verdun at about the same time, I believe that the first unit to get them was Sturm=Bataillon Nr. 5 (Rohr)
, the famous Storm Battalion Rohr (which my father fought with several times on detachment), and possibly the second was my father's unit, Garde=Reserve=Pionier=Regiment (Flammenwerfer)
. But at first the line infantry regiments did the same, as they came out of line they handed their helmets to the men of the relieving unit.