Brad Stafford from Down Under raised this question ages ago:
“Any chance of finding out where the phrase short shrift derives from?“
Indeed, that is no great secret. Shrift means “confession, penitence”. Shrifts usually require long penances, sometimes up to a year or even a life-time. Short shrift was a brief penance given to a person condemned to death so that absolution could be granted before execution. Presumably, any shrift would be too, too short in that situation.
The verb that this noun is derived from is shrive, shrove, shriven “to listen to confession and render absolution”. It comes from Latin scribere “to write” and shrift from Latin scriptus “writing”.