The general rule is that you water your tomato plants when the top 1″ or so of soil is dry. I don’t mean if it feels dry on top, you need to stick your finger in and if it feels dry on the top 1″, then it is time to water. Tomatoes love moisture but don’t like to be flooded with too much water. Too much water can prevent air exchange in the soil and roots. You learn how often you need to water your tomatoes after a while.
When watering, flood the soil the tomatoes are grown in, if growing direct into the ground. You may need to soak the area multiple times to get water down deep enough. For pot grown tomatoes, I usually water my tomatoes until water starts coming out of the bottom of the pot. When watering tomatoes in the ground, use a hose for thirty seconds to two minutes per plant, it all depends on your area and local weather conditions, types of soil, etc.
It is best to water tomato plants in the morning or late evening so your tomato plants will be hydrated before the sun gets out and the plant starts producing usable energy. I used to use a watering system to water my plants at 7am every morning, and it worked great for years. Now I wake up at about 8am every morning and incorporate watering tomatoes into my getting up and going routine.
Personally watering your tomatoes will increase the quality for most people. While the plant may receive imperfect watering, you will see the plant every other day or couple of days. I noticed that when I had an automatic watering system, it was easier to neglect the plants for a week or two. If that is what you are looking for, a self watering system would be great for you.
In the summer your plants will be needing to be watered more, but still not over watered. Water when the top inch of soil is dry still, but it will happen more often. After the ground has started to heat up from winter, you can use a mulch on top of your soil to conserve moisture.
Watering tomatoes in containers is basically the same except you might have to do it more often as containers generally dry out faster than in the ground.