I did one (first) right at 4k for a couple of reasons. The first was my engine, 2.5L altima is noted for a pre cat issue which has destroyed some motors. Second I had a mix of severe, short commute and non severe. So, I wanted to be on the safe side.
UOA came back excellent with a recommendation of 5k, so that's what I plan on running fom now on. Not planning on another UOA, for a while.