We water our flowers every night. Sometimes on the really hot days we water them in the morning and in the evening. It doesn't matter what they are or where they are, we water daily.
My wife waters the flowers daily too (especially when it's crazy hot out). The hanging baskets tend to die off if she doesn't. She says it is because it is a different soil.
Normally we would water flowers every day, but there's been so much rain this year that we haven't had to. Even when it doesn't rain, the ground is pretty saturated.
We water the flower boxes (they don't get much rain) and the hanging baskets every night. The flower beds aren't watered nearly as often because of the rain. If the flowers look like they need it, we water them.