It's not duh, everyone forgets that stuff if they aren't teaching it! They retrain us in it all the time, too!
I'm not kidding, every few months it comes up in our trainings. I do this as a whole-class activity with every selection because if I don't, I know my kids will forget it (keeps me fresh, too
). It helps them a lot with their decoding skills and it only takes a few minutes.