I grout all these joints and haven't had issues with my Schluter shower.OK, so I know that inside corners in a bath/shower should be caulked, not grouted. Does the same hold true for an outside corner? Example: the top of a shower half wall (glass on top half of wall).
Perhaps using single component grouts has eliminated some of that. My cement grout in the bathroom has chipped to hell in the corners...single component has been fine.In any change of planes on tile, you should avoid grout. You can get color matching grout caulk (sanded or unsanded) and it will expand and contract accordingly. Grout will almost always chip out eventually.