Probably my hardest scenario wasn't anything to do with a procedure, it was a strange scenario.
MD-88/90 initial training. Another pilot in the left seat on his initial captain checkout.
Our very first V1-cut.
V1 was say, 145 knots.
My takeoff.
Background: At my airline, once the power is set, the captain keeps his hands on the throttle to command an abort if needed. Regardless of who is flying the aircraft during takeoff roll.
About 130 or so knots, we have an engine failure. He doesn't verbally announce it, so using good CRM I announce "Engine failure!".
No response.
I look down at my airspeed again, and we're at V1 now and slooooooowly accelerating towards Vr so we're kind of already committed to taking off even though we're not going to have the performance.
The end of the runway is rapidly approaching (typcal balanced field length scenario) so I manage to get the airplane 'unstuck' and in a flying attitude and finnese it off the ground through a combination of tickling the stick shaker and increasing power on the operative engine to almost to the point where I was running out of yoke/rudder, etc.
It worked for a while but we ended up impacting terrain.
So the difficult thing for me was to figure out if I would have aborted, or figure that the captain was having another airspeed indication (when you start dropping generators, some aircraft can give erroneous instrument indications) or that I did the right thing by actually trying to fly a doomed aircraft after the captain failed to abort prior to V1.
Flying the sim and following a checklist isn't hard. You earn your money by reacting correctly in a high-pressure, non-standard situation that you can't teach with no do-overs.
That's why I say that you can teach any 200 hr n00bie to fly an jet and read a checklist, but decision making... Training is NOT a substitute for experience.