Have you ever been in the middle of an operating session and disaster strikes? A train derails, shorting out the DCC system, taking with it a power district, or even the entire layout. The problem is eventually fixed, but in the 5 minutes it took to restore things to the way they were, your fast clock kept ticking away. With a 3:1 ratio, all trains are now suddenly 15 minutes late.
Wouldn’t it be nice to simply press a button on the fast clock to pause time, then with a single press, restart the time right where it left off?