Overwatering causes more plant deaths than any other factor. Too much water in your plants container is ALWAYS a bad idea. It is best to err on the side of caution.
A day before your plants wilt from lack of water, the lower set of leaves will droop a bit for a whole day. You NEVER want to let your plants go into a full wilt anytime in flowering and particularly after the halfway point as it can cause your plants to turn into hermaphdites. Overwatering causes a scarcity of oxygen for the plants roots, so TLO micro life populations diminish. This can lock out nitrogen or turn it into a gas. Overwatering encourages anaerobic micro life.
Anaerobic soils have very little oxygen present - for instance the wet, waterlogged, marshy soils in a bog. While anaerobic conditions are important for some processes, such as bacterial reduction of nitrate to nitrogen, these conditions can also produce hydrogen sulphide, methane and other undesirable substances.
Source for quote: Cranfield University
I let my plants dry out when I am treating for those pesky gnats especially when I use diatomaceous earth because it gets soggy.