All your comments are greatly appreciated. They help me to realize what is going on so that I can avoid proglems down the road and meanwhile avoid giving my plumber any uncalled for grief.
After the soft copper was threaded through running though core holes in joists/beams, which was very difficult as the cores were slightly off center which made it tight, sythetic grey inserts were fitted around the copper and then pushed up into the holes. Because the pipe was tight against the wood, the insulators had to be knocked in with a hammer. A third of the holes have no isolators, since the pipe was so tight against the wood.
Is the absence of those isolators likely to cause a rupture from the wood and copper rubbing?(I know that it can contribute minutely to the transfer of water noise, something that does not seem to be a problem.) Thanks.