I watch Air Disasters on Smithsonian channel. All those years in a single engine plane. I'm glad we never had a problem.
Many years ago I was dispatched to deliver a set of blueprints to an important client in Florida. Trip down was uneventful, delivery was made, client was happy with the plans. All good.
The client said his private plane was going to be flying back to my home state (also the client's home state) with no passengers, so he suggested that I cancel my commercial reservation and hitch a ride with his pilot. No problem! So, bright and early the next morning we took off in a fairly new twin -- Cessna, I think, but might have been a Piper. (It was a prop job -- no Lear Jet for me). Since there were no passengers, I got to sit in the right seat.
Take-off was uneventful but the pilot seemed to be looking at one part of the instrument panel quite often. We were still climbing out when the pilot SHUT DOWN THE RIGHT ENGINE* and called in a Mayday. Oops. Back we went. He made a picture perfect landing, we taxied back to where we had started, and I prepared to disembark. The pilot was just sitting there, so I asked if he was coming.
"Just as soon as my knees stop shaking," he said.
So, yes ... it's all well and good to have a spare, but even in a twin losing an engine isn't a cakewalk.
* The engine was losing oil pressure and the temperature was climbing rapidly.