We were doing it maybe once a week, we could stretch it to two.
Sherman, however, doesn't understand that poop is to be avoided (thank God he doesn't eat it or mess in his crate, and he still poops towards the outskirts of the yard), so he'll happily lay down on/near a pile of poop in the yard. That coupled with more fetch being played and more excursions into the yard in the dark being needed for potty breaks, I think we're going to have to start scooping twice a week.
We just use a pooper scooper (metal pan with handle, and a metal wedged scoop with handle) and dump it into our "poop bucket" (metal trash can with a trash bag). That gets taken to our street garbage can when it's full (maybe once a week, between the cat litter, Guinea Pig shavings, and dog poop).