Technique not SOP. I find selecting speed vs mach on the CEO makes the a/thr much more active vs the soft capture
In both those photos, why can't you just bug up to .78 or higher? We run our 321s frequently in smaller margins than that but I find having selected .79 or .80 to be the best way to not worry about it. I would probably not let the plane ride at that low of an airspeed.