Anyone who knows me knows that I don't encourage anything to be done in practice without a purpose. Every drill we do or every set in which we grind through all has a specific goal in mind - a lesson, a skill, a concept for swimmers to grasp.
That is why I often read anything put out by The Race Club (theraceclub.com). The club is headed by former Olympian Gary Hall, Sr. and posts science-based material in an easy-to-understand format. For instance, their recent post on rotation was most interesting. It is eye-opening for swimmers to grasp that they must 'make rotation happen', it is simply not just going to happen on its own. The benefit? Lat engagement and torque power. Read here for more info on the concept of rotation in backstroke/freestyle.