"The problem with locked timing is that the timing is locked and nowhere to go" but to detonate and no compensation. This is where i'm at. If you tune it the way you described instead of adding timing under acceleration and load where fuel quality decides if it pings you have the vacuum advance which actually reduces timing and eliminating the chance of ping as the timing goes away under load. My cars have never stumbled using this method. AND they run cooler this way. I also get beter mileage than the other guys IF they can keep their hot rods running.