Well, if you take your lens out and take it into daylight, you're actually killing the fungus spores. I know a photog who specializes in landscape photography. He has never owned a dry cabinet, and his lenses are over 10 years old and no fungus ever, becasue he's out in the sun a lot.
If, on the other hand, you keep your lenses indoors for long periods od time, a dry cabinet is a must in SG.
I guess for Singapore weather should be a few days to a few weeks.
Just do not take chances. Fungus will grow when you most unexpected it to happen.
Some of my own personal tips.
1) Try to use your lens at least once a week.
2) Before storing in your dry cabinet, twist the zoom ring a few times, and wipe the external of your lens body with a clean dry cloth.
3) If you are not using your lens for that week, remove the UV filter, and try to expose the lens to direct sunlight for a few minutes. Zoom in and out while you are doing this. After
that screw back the UV filter and return it to the dry cabinet.
The above tips are not scientific, so try at your own risk. :bsmilie: