The best Sim. sessions for me have been where I have walked out afterwards thinking I have learnt something new today, or I have cleared up something that I had forgotten.
The worst sim. sessions have been those where the sim. instructor has felt that they have had to run through their full repetoire of failures in an attempt to try and show how clever they are. I also used to dislike the instructors who felt they had to load you up until you broke and only then could they re-build you.
Sometimes the most informative/thought provoking sessions have been the ones where the RTO was carried out at a benign speed, not V1-5Kts at MTOW. Where the pressurisation problem was controllable, and didn't need the O2 masks on followed by the high dive. Where the engine could and should be re-started after a flame out! What do you do now it's re-lit? Continue knowing it failed once, or return in case it fails again? Plenty of scope for CRM there!
The simulator is a training aid not a trapping tool.