Any of you ever seen how much a T tail vibrates and flexes when one engine is at high power and the other isn't?? It's scary. Anyone remember the Nomad? Years ago I was shown 1500 on both for pitch/feather check, then one at a time to mag check rpm, leaving the other at 1500, to help even the load on the nose leg and the tail structure, especially T tail types. Dunno if it matters much, but it has always worked ok for me.......