[hueving]

Not really, it's not predicting the future like a gambling system. It's just a measurement people are familiar with because they have reference points in mind.

[kazagistar]

The phases of the moon are also a familiar measurement system for which people have reference points in mind.

[grogenaut]

The phases of the moon are pretty good for predicting moon rise, moon set, time of month, days of the year, days, and the tides.