Cant imagine the Janet transits are that long either, likely less than 20 minutes tarmac to tarmac, so they likely have a small fuel fraction as well.
My shortest jet leg was Kauai to Hono, with the MD-87 captain announcing a 16 minute travel time. First hostess came by literally tossing out small pull top POG juices, followed by second hostess about 90 seconds later with the trash bag.