Fully concur that too many instructors are tempted to load up the student with multiple emergencies. The usual reason is that if you can handle such a complex situation you will be fine in the more simple ones. The argument against is that whilst when you are left with nothing but your seat height adjust and your dog tags to fly an IMC approach anything you come up with is fine, but most real cases do not require such improvisation. The ability to apply correct checks and procedures can only be tested with simpler emergencies.
As with all things in life balance seems to be the key and thus overemphasis on complex multiple emergencies seems counterproductive.
Having said all that I remember some mates in a Royal Navy Sea King having an engine failure on take off from a frigate and whilst circling to land had a completely unrelated aux hydraulic failure. As Old Fella said 'sme days it is best to stay on the ground.'