watering a raised bed
Although it is less likely, yes, you can still overwater with a raised bed, it all depends on the type of soil and how long you water. The best way to check is simply to stick you hand in the soil and see how moist it is.
Here are some general tips:
Water in the morning, rather than at night
Try to avoid overhead watering: instead use soaker hoses or drip irrigation.
These two practices will reduce your chances of diseases, especially fungal diseases and it will save water.
If you do have soaker hoses or a drip irrigation system, you might as well add a timer to your spigot!
It is better to water deeply once a day, than shallow multiple times a deep. Watering deeply will encourage the roots of the plants to go deeper into the soil, rather than just hover at soil level. That way, your plants will be able to get to water, even on a a day that you may not be there to water.
Hope this helps.