The OHJ is a rather old method from the times of no radios. It was meant to check the wind direction, possible other traffic and runway condition. Consequently it is flown left turns, so the pilot is able to actually see all that. Nevertheless, you always had to be prepared for somebody else choosing a different runway to check in OHJ, because thinking of another wind direction initially. Btw, I think we should have call it different to 'overhead' as it tends to confuse, as it is more a 'over outside downwind THR' - many not acquainted start OHJ with a midfield, which might be dangereous at glider sites.
Also, beware of OHJ on the continent without checking the AIP first!