With a long running campaign it's common to end up sitting on a demographic time bomb: your most experienced personnel are the oldest, typically there from the start, and the random death equation eventually starts catching up to them. With that in mind, is it better to start rotating these people out of important positions early, perhaps sacrificing their valuable skills? Or keep them in and backfill their positions on an as-needed basis, which lets them be of full use but potentially leaves things in the lurch if they die at an inopportune moment?