We arrived in Ranthambore in the evening, unsure of what to expect for the following days.  Anil, upon seeing our initial itinerary which had only one drive, told us we absolutely needed to add at least one, but preferably two additional drives to increase our chances of seeing a tiger.  Even with these two more drives, he made sure to let us know we shouldn't expect to see anything, as tiger sightings are incredibly rare.