I'm using these bits to drill granite prior to loading the holes with expanding grout. Most holes are 14". I get about a dozen holes before the bit starts to slow down due to wear. With care, I can get another dozen before the bit is too worn. Heat and pushing the drill too much shorten the life of the bit,
Although it was smaller than I expected( because I misread the size as 1 and 1/16 instead of 11/16). It performed better than expected. I was able to bore through caliche' in half the time of my previous drillbit.