Surely if the gliding site actually has a passing height on the charts it's almost better to transit centrally overhead and avoid them that way ?
Otherwise why bother with any height - or 'ATZ' ?
Going to one side or the other, IMHO, even outside the circle on the chart offers a greater risk of intercepting glider(s) departing or returning. Overhead at the right height is acceptable over airfields
As for the implication above that motorised pilots don't look out enough, especially when poor glider pilots are apparently too busy themselves to ditto ? Well I ask you.
All pilots must keep a good and frequent scan look out, regardless of what a/c they happen to be in.
mike hallam.