[ShrimpBurrito]

If you want to get a bit more technical, pick up a hygrometer. Even better, get a wireless one that measures indoor and outdoor simultaneously. They are cheap. That way you can assess at a glance if it is more humid inside than outside, which would be a good time to ventilate. There is certainly no point in ventilating when it is more humid outside.

In many regions here in the southwest US, there are huge intra-day swings in humidity. Often more humid in the morning and drying out as the day goes on, it could be in the 90%-range in the morning, and then 30-40% by afternoon.

A hygrometer would also give you an indication as to whether your ventilation methods are adequate, and when perhaps "enough is enough".

Dave