Azaleas like to keep a fairly consistent moisture level. Over watering will kill the plant by drowning the roots, not allowing the soil to keep a good level of oxygen. The roots will get root rot and will eventually kill the plant.
Sign Of Over Watering
Unfortunately the signs of over watering are very similar to the signs of under watering. The plant will show signs of distress when the tips of the leaves start to turn brown. Do not react to this by watering it more thinking it is dry or under watered. When the plant is under watered the tips will also turn brown but it is usually accompanied by or preceded by limp and wilting leaves.
Testing Soil Moisture
The best way to figure out your watering frequency you should use the finger test. Stick your finger about 4 inches into the dirt. If it feels moist you do not need to do anything. Check it again at the same time of day each day until it feels almost dry about 4 inches into the dirt. If it is wet and it has been a few days since it last received water determine the cause of the poor drainage and take appropriate measures to fix the problem.
When it is dry or almost dry water it well and make a note on your calendar of the date. Continue doing the finger test every few days and marking the watering days on your calendar until you have a good pattern down. Then you can just follow the pattern and not have to continue with the finger test. Different climates will require different watering schedules.
Soil Moisture & Seasonal Changes
If the temperatures change 10 to 15 degrees either higher or lower and remain there for more than a couple days do the finger test again and adjust the amount of watering as needed. Do the finger test during seasonal changes to stay on top of your azalea's watering needs.