If your shouldComponentUpdate always ends up returning true, then any time spent in that method is wasted, because you have to go update the component after tha

If your shouldComponentUpdate always ends up returning true, then any time spent in that method is wasted, because you have to go update the component after that. And as React becomes more and more optimized, shouldComponentUpdate becomes less valuable. It is rare to have an expensive shouldComponentUpdate that returns true most of the time, but there is definitely a trade-off there that depends on the specifics of how data flows through your app. People like to put it on everything but we (React team) believe that it's probably best to put it in a few well-intentioned places. This tension is something we're actively thinking about.