Question for "Blow Out the Water Line" gurus

I have blown out the water lines, etc. in my FWs for the past 15 or more years with only one problem. Something happened to the main line and it split right under the shower pan. Pulled up the pan, found the split, called a dealer and they were able to get to it that morning. I might have forgotten to open the low point drain lines. Pulled it down there, waited around and an hour later it was fixed. They didn't put the pan back in, but since I took it out, I put it back in. That is the only problem I have had while blowing out the lines with compressed air. I use a 6 gallon compressor and now set the pressure at 50. Maybe I should go back up with my pressure.