There's a scan feature on my Rino 110, that scans all the channels, and "subchannels". So there's no luck involved at all. Just click on Scan, and it'll find the channel, and subchannel with activity.
The subchannels aren't really subchannels, they're just squelch codes. and it merely filters out everything that's not on your code. So if you're on Channel 4, Code 12, you only hear broadcasts on 4(12). But everyone on Channel 4 and NO code, will hear you too.
And there are still FRS radios sold without the subchannel feature.
-patchy