Hell Man
I had the Compressor Drive shaft shear in an Agusta A109C, total power loss from that engine with TOT off the clock.
That said, I also had the turbine let go in an AB205, total and instant power loss.
No pre-determined cause in either instance, just the 'sh1t happens' category.
So that's one all in the single / twin argument in my personal experience.
JJ