@EdFred,
@TCABM, guys, I'm not disagreeing that preparing for diversions is important. Come on now.
But if your student planned a flight from A-B-C-A, and you sneakily want for them to actually fly A-B-D-A, and plan to endorse it as such, how can you endorse that you reviewed their planning? You reviewed it for A-B-C-A but are endorsing A-B-D-A. Therefore, you didn't review what you planned for them to do. You didn't review their route from B-D-A, selection of checkpoints, knowledge of the runway layout at D, etc., etc.
Again, I'm not opposed to the IDEA, and knowing how to divert is important and a normal part of training. I just can't see the idea squaring with the regulations requiring you to review their planning, if they're not flying their plan because of an intentional mid-flight change by you.
And the issue of a real emergency or divert is a red herring. That's not what we're discussing. I would expect the student to take appropriate actions in those situations. And if they end up at an airport not in their original plan or endorsement with a flyable airplane (let's say they diverted for a door that popped open or something), then I am required to review their planning to get home and issue them an additional endorsement for that flight.