Not by choice - by necessity! When the old bike have let you down and left you on the shoulder for a couple of times, you retreat to the study and get wiser π
Shout if you want a couple of links / information about 1) mechanical rectifying, 2) electromechanical voltage regulation / alternatives and 3) "budget constraints" workarounds.
Voltage regulator for Gilera Sport (6 volt DC). Very condensed checklist: File / clean contacts INSIDE regulator before first start - check voltage before after engine start (at medium rpm voltage higher than battery voltage tho never higher than 7.2 volts).