Some people like to do it for entrelac when you have lots of rows that work 2, sts, turn, work on the same sts, turn, work 3 sts, turn, work the same sts, turn, and so on. I don't mind turning as I found that knitting backwards more fiddley and uneven tension was more of a pain than turning. Though I sometimes knit backwards if I'm fixing a row with a lot of stitches and had to take out a bunch of rows in the middle. But as a standard technique instead of purling a row, only a few people do do. You tube will have some videos showing it.