Why Short Exposures Under Light-Polluted Skys?

Can someone e explain the advantages of taking a greater number of shorter exposures under light-polluted sky's compared to fewer longer-exposures?

I'm under a Bortle 6-ish sky and usually shoot 2 to 5 minutes exposures. Should I switch to shorter exposures?

Does this change if I'm using a dual-narrowband filter like the SvBony SV220?