Your goal should be a self-sufficient flower border. If you water every day, you will always have to water every day. Normally, 1" of water a week, either from you or Mother Nature the first year is enough. You want it to soak deeply so that the plants will send their roots down to look for water. The second year, you can water every other week, more often just to help them through droughts, or if wilting before lunchtime.
If you are worried or want to test, you can tell if you’re watering enough if you dig next to a plant after watering and see how far down the water has penetrated. Water should soak in about 6 inches. You’ll get a feel for how much water is needed to reach that.