I think that the notion that a pipe "needs to rest" has been taken out of context and, forums being forums, now just keeps being echoed in its chopped-up version. Let me try to explain its origin the best I can remember.
During the time when ASP was very active, in its early years (late 90s), there were many discussions about pipe cleaning. One of the questions was how thorough of a cleaning should a pipe go through between smokes. In the midst of this discussion, there was one dude that decided to do this experiment: if all we do is to run one cleaner down the pipe after smoking it, how long do we have to let a pipe dry between smokes so that it never goes sour (i.e., where perhaps we wouldn't have ever to pull the pipe apart for deeper cleanings). Unfortunately, I forget the name of who did this, but that guy carried out the experiment. He found out that, if he let the pipe rest for one week between smokes (one week or more, obviously), he could smoke the same pipe over and over again without having to clean it, and the pipe would never sour. In other words, if he didn't clean his pipes, he could let the pipes rest for one week and then smoke them again, over and over, without further worries. Or something like this.
Well, the rest is history: people started repeating his idea with fewer and fewer details, and soon it mutated into the concept that pipes must rest between smokes, without further explanation given. Note, however, that this was not the original concept, just a severely mutilated version of it. Hope this was entertaining to read. And, perhaps, a lesson to those who keep parroting what they read on the internet.
During the time when ASP was very active, in its early years (late 90s), there were many discussions about pipe cleaning. One of the questions was how thorough of a cleaning should a pipe go through between smokes. In the midst of this discussion, there was one dude that decided to do this experiment: if all we do is to run one cleaner down the pipe after smoking it, how long do we have to let a pipe dry between smokes so that it never goes sour (i.e., where perhaps we wouldn't have ever to pull the pipe apart for deeper cleanings). Unfortunately, I forget the name of who did this, but that guy carried out the experiment. He found out that, if he let the pipe rest for one week between smokes (one week or more, obviously), he could smoke the same pipe over and over again without having to clean it, and the pipe would never sour. In other words, if he didn't clean his pipes, he could let the pipes rest for one week and then smoke them again, over and over, without further worries. Or something like this.
Well, the rest is history: people started repeating his idea with fewer and fewer details, and soon it mutated into the concept that pipes must rest between smokes, without further explanation given. Note, however, that this was not the original concept, just a severely mutilated version of it. Hope this was entertaining to read. And, perhaps, a lesson to those who keep parroting what they read on the internet.