MB in MB:
+1 and AMEN to your handgun reloading in units of 50 at a time, and over viewing all 50 cases to ensure each has powder. If one case does not have powder, your eye (MY eye, anyway) will IMMEDIATELY be drawn to the empty case - as it will not conform with the visual pattern. This powder check is an "unintended consequence" of using a single stage loader. This particular check doesn't exist with a progressive loader.
Just my $0.02, your mileage may vary.