A method for programming a plurality of data sequences into a corresponding plurality of flash memory functional units using a programming process having at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, the method comprising providing at least one indication of at least one varying situational characteristic and determining a value for said at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and, for each individual flash memory functional unit from among said plurality of flash memory functional units, programming a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter, said at least one selectable parameter being set at said value determined for said individual flash memory functional unit.