If the parent is referring to de Bruijn sequences then it should in theory be 100% reliable since the device will be traversing every permutation.
I suspect the 70% success is more to do with mechanical reliability, since the device must be compatible with multiple different mechanical combination locks that have different physical characteristics and may be far from in perfect operating condition - and also be able to operate at a reasonably high speed to be able to traverse all combinations in reasonable time even when using a de Bruijn sequence.
I suspect the 70% success is more to do with mechanical reliability, since the device must be compatible with multiple different mechanical combination locks that have different physical characteristics and may be far from in perfect operating condition - and also be able to operate at a reasonably high speed to be able to traverse all combinations in reasonable time even when using a de Bruijn sequence.