These recommendations are made for the following conditions.   

* Ambient RH: 50%     * Ambient Temp: 20°C (68°F)     * 500g (1 lbs) filament spool

Actual drying time for a filament may vary under different environmental conditions as well as the initial water content levels in the filament.  In addition to drying prior to 3D printing, drying the filament while printing is always recommended.