Few if any Cirrus chute deployments have "failed" but one could argue that many, possibly most, of the situations where the chute was pulled would have been better recovered conventionally.
The unquestionable uses of a chute are
- over forest
- over rough terrain
- anywhere, following loss of control due to aircraft-technical failure
- pilot incapacitation?
- over water
But pulling the chute when over a load of green fields, following an engine failure, is nuts. I also don't get why one of the pulls was done due to a missing aileron. You don't need both ailerons, or indeed any at all.