Depends on the relative humidity in your house and the type of filament you use. I have usually ~30% humidity in my flat.

• PLA reall doesn’t care about humidity. I’ve got some 5yo rolls that still print like new, without storing them air-tight.
• PETG is fussier. After a few days they start to act up. I always have them in the filament dryer while printing.
• Specialist filaments (e.g. Nylon, Carbon, Wood) might be much more hydroscopic, depending on the material.