What unit of time is set to cache your module?

Let me ask you a question.
In general settings joomla. Selected "standard caching."
I entered "360" (ie 6 hours).
For your own module (as I pointed Embroidery) is worth the value - 900.
Your module is updated in 360 minutes?

in fact, what is exactly the problem with this cache settings ? I don't really understand what is the problem

PS : for information, this is the standard joomla module cache, and this is managed by joomla itself like for any other module