Not sure about how many miles between cleaning. It would depend on the conditions driven in. I'd suggest just do an inspection of the filter periodically to see how dirty it is.
I only clean mine ~50K...or so
I take it out and dunk it in a bucket of orange cleaner, water and CLUB SODA.
Then I let it sit in the bucket a bit..whatever..then dunk some more.
I change it out and do it again sometimes.
when I am satisfied with the look, I rinse the crap out of it with water dunks.
I then spray it with with baby oil (mineral oil) and alcohol (shaken not stirred) in a spray bottle in side and outside the filter and let it set over night.
I tamp it dry with a cloth and put it in the car, then run the car good down the road a bit..
Then I clean my MAF, IAT..etc with electrical cleaner.
I've done it twice so far. (134K miles)
Let the shit-storm begin...