Occasionally I would hand fly the 757 on wet compass and emergency altimeter, AS and attitude indicator just to get the scan working. Everything else was still fine but didn't look at it for a while. They put that emergency stuff in airplanes hoping you can use it. Training doesn't because they have too many other squares to fill. Starting out in an Aeronca champ 7AC with no battery but needle ball and airspeed made the 757 on standby instruments easy. For you younger guys we had a venturie tube that made enough suction at 70 mph to keep the gyros spun up. Not like the AB laws we only had one level of automation, none. It worked just fine. If all else failed point south, pull the power back and descend with no gyros using compass lead error to stay on heading. It works in all aircraft, big and small. At least in the northern hemisphere.