My perspective is from primarily same day returns for 1-3 teeth, relines and repairs.
Mount for any case that involves adding or changing teeth when the DDS provides opposing.
The bite is ground in to any new teeth, they should take less than 15 minutes to see the patient for delivery. This is for add a tooth and new immed rpd prosthetic.
Duplicate any case that I have time to do it, always for greater than 3 teeth. 4 teeth and more always get duplicated. You usually will deface the model somehow.
Add a clasp I prefer to mount so I can see the interplay between the antagonists, sometimes there is a bite gap and I'll do a transocclusal ball clasp, keeping it out of occlusion, if there is supereruption or other issue..Again, depends on what is sent.
Repairs of fractures, it comes down to what time the dentist is willing to put into it. Most will send just broken pieces, rarely they will tack them together and pickup impress, some will take an impression without the prosthetic. Frankly, I prefer they don't tack and impress, it is too technique sensitive to do both rapidly and accurately in most offices.
I'm not a speed champion by any means. I do however make sure I give the best result possible with what I was provided. So it really comes down to what was provided.
Sometimes an add tooth and clasp comes with just a pickup impression of the working side. Sometimes I get more. Just depends on the doc's style and whether they prefer to put work in front of or at delivery.
Mounting is built in to the fee schedule for complex repairs, adding teeth and adding clasps. Duplicating is built in for immed RPDs.
Duplicating fracture repair models is not something I do regularly, but it has utility and value.
And I totally agree with RKM, ask them when you return. They may be trying to do the best possible work, which is a pretty awesome problem to have.