It’s not normal operation. It is an emergency measure that takes effect with the network is in a hopeless congestion condition. And in my experience, this approach changes the recovery time from several hours to several minutes.
About what numbers of phones are we talking here to reach a critical mass? Usually a phone transmits two or three access bursts, then it waits for a while, and I mean to remember some slotted aloha scheme, or similar. I hardly can imagine that such a condition could last for_hours_, but of course the real word sometimes offers bad surprises :)
Ralph.