How often should I change my stock air filter?

I own 2011-2012 Ford Crown Victoria and I live in Riyadh, Saudi Arabia, which is known for the huge amount of dust in the air, to put it into perspective a car would gather the same amount of dust on its surface in one week the same as a car in any "normal weather" country would have gathered in a month or two.
So should I change in the manufacturer s recommended service time period or follow some short time period, even though it does say in the manual if operating in dusty conditions check frequently and change if necessary but I'm not sure how necessary is necessary. One more question; if operating in these dusty conditions, is just blowing pressurized air onto the filter (when it's out of the air box of course) enough?

Due to your conditions you may have to replace the filter every 10k miles, or less. Between chances, yes, you would be wise to clean the filter, with pressurized air, every few k miles.

The interval to change the filter is NOT measured in either time OR miles. It is measured in the amount of dust that accumulates on the filter. Some filters are designed to be cleaned and reused indefinitely. Most will be destroyed by any attempt to clean them.