let us qualify that
don't add anything if your sticks are already at optimal for you....
and you don't intend to open it every five minutes to show it off.
If I am going out for more than a day, i usually add 1 or 2 drops (as is eye dropper) of distilled water to that lame little humidifier that is included into
most of them.
The volume is small, and so it loses humidity fast if opened frequently in a dry location.
YMMV