Ask at the forum if you have an Ancient or Modern Greek query!
P. and V. πολλάκις θαμά (Plato), P. συχνόν, Ar. and P. πυκνά, Ar. and V. πολλά.
oftener: P. πλεονάκις.
oftenest: P. πλειστάκις.
how often, indirect: P. ὁσάκις.
as often as: P. ὁσάκις.
as often as possible: P. ὡς πλειστάκις.