I have been able to get more fastpasses per day than in the past, especially for a Magic Kingdom day. More important to me is being able to set up fastpasses for multiple parks in a given day, without having to exhaust my early selections. So if I want to go ride Remy in the evening at Epcot, I have the ability to purchase that in the morning while rope dropping and selecting fastpasses for DHS (ToT, MFSR, etc). Some of my success is due to a reasonable understanding of how the system works, and when to make my selections.
Now I've had some great days in just a single non-MK park as well, even at crowded times, but my results seem to be better than others trying to book during similar periods.