> Let's say I'm a mad bomber. I hide bombs rigged with cell phones at a few key locations and wait...and wait...and wait. Those bombs aren't necessarily going to be found. I have carte blanche to just wait for weeks and then detonate when the moment is right. Is that realistic? Maybe...I mean, it's all about that stealth-check, right? A bomb could be that skillfully hidden in real life.
Well, the longer you wait, the greater the chance of the bombs being discovered and disarmed. In fact, someone might find the bomb, disarm the bomb, and keep the phone in order to catch you out when you call to detonate!
And this is what happens with land mines and cluster bombs. Bombs are laid down, and lie for months, or years, before they are discovered, usually by taking someone's leg off.