I say almost never. But I will note that I appraised an 8000 SF home once that was used for entertainment. The kitchen has a walkin freezer, 2 commercial ovens, and a pantry that was about 12 x 20....I have bedrooms smaller than the room that housed the sound & telephone system.
99% of the time - no. If however the pantry is exceptionally large with food prep areas and perhaps additional sinks, stoves and refrigerators, I think you'd be justified to call it a secondary kitchen. I've seen 2 that I'd consider as a separate room, both years back and don't remember how it was dealt with at the time. :usa:
I'd say "it depends" on the size of the pantry. I've seen some that are little more than overgrown closets. If you open the door, stick in your arm and pull out the can of soup, that's all there is to the depth of the "pantry". So no, I don't include that as a room. However, I've been in several multi family dwellings where the pantry holds cabinetry, the sink, and sometimes the laundry area. I call that a room because of the function of the area. I show that on my sketch, and will put 1 in the "other" box on page 1 of the 1004 or whatever form the client ordered.