Hiding empty staves - what about piano?

It's common to want to hide empty staves in a score to save space. However, a question arises in ensembles containing piano: should the piano staves be hidden individually (so only one staff shows if one hand plays but not the other), or all together (so either both staves show, or neither do - never just one). In jazz, the former is common, but in classical music, we usually want the latter. In this video post, I show you exactly how to achieve both of these results.