My outfit, a well known 'High Cost Operator'
requires that except in clear daylight VMC, when the flight crew can unequivocally confirm that an impact will not occur, they must react immediately to a GPWS warning.
However, they do go on to point out that crews should beware of being slow to react on the basis of previous suspect performance,and that investigation of the reason for the alert or warning must take second place.
All seems reasonable and sensible to me !!