Sometime in the late 80s thought was that if we taught patients to give themselves their own insulin and not double check that there was no reason for nurses to double check. Well, times change, things happen (sentinel incidents) and what looked like "old school" practice becomes standard practice again. I have worked places where insulin, heparin, dig, and a few other things were double checked and documented. Here and now, the double check is done but there is no documentation. In Peds, Nsy, NICU they double check all drug calculations. It does make sense.
With medication errors being a national patient safety issue, better safe than sorry.