What is a good failure chase

0% is best. 100% is the worst.
5% would be a high amount. It doesnt happen once every 20 times like the math suggests.
Its more like every 5-10 times.
Reason being is because every opportunity is another 5 in 100 chance to fail.
It re evaluates a fresh cycle every time.

Of like a part of engine blowing up or shutting down