on some amps it’s not necessary. Amps like a 2203 or other amps that have voltage balancing resistors on series power caps will drain through those. That said every guitarist should own a basic multimeter. I never drain but will check the voltage with a multimeter.Do u guys (and gals) do this every time your chassis is out of its cab? I’ve heard people say to do it. I’ve never done it. I just poke around a bit but haven’t done I guess because it depends on what maintenance you are doing?