This video illustrates the biggest challenge in the war on pinhole leaks in copper pipes for Orange County, CA.  https://youtu.be/WRn3CHMXM9o

Most people just want to repipe with new copper or PEX.  They probably don't need to do either one.  The copper is fine.  It just needs to be protected by removing the chloramines that cause it to break down.  It really is a simple fix and the least expensive option.