The pilot reported that she was practicing three-point takeoffs and landings in a tailwheel-equipped airplane. The first three takeoffs and landings were uneventful. During the landing roll of the fourth landing, the airplane began to veer to the left. The pilot applied full right rudder; however, the airplane continued to the left and exited the runway onto a dirt surface. As the pilot added full power to attempt to avoid a taxiway sign and return to the runway, the airplane briefly became airborne before pitching down and pivoting to the right. Subsequently, the left main landing gear collapsed and the left wing struck the ground resulting in substantial damage. The airplane skidded nose down until coming to a rest. The wind was reported to be from 110 degrees at 7 knots at the time of the accident. The pilot reported no mechanical failures or malfunctions that would have precluded normal flight.