Hi. Yes, you are right about deep watering being better than frequent shallow watering (as noted in this brief article from Purdue U.). In general, watering once to twice per week should be sufficient, but that depends on the weather and your soil; sandier soil holds less water and may require more frequent watering than soil that holds more moisture. The key thing to key in mind is that vegetable garden plants generally require about one inch of water per week, and you should provide whatever Mother Nature does not; therefore, you should have a good rain gauge so you know how much water your garden receives. This article from the U. of Minnesota provides some additional tips for watering. It recommends watering twice per week for sandier soil and just once per week for soils with more clay or organic matter. It sounds like you are hand watering, so you should try to get some idea of how much water you are providing each time you water. I suggest watering in a 5-gallon bucket for 20 seconds to see how much water you are actually giving each plant; that diameter should be a reasonable approximation of the root zone for a typical garden plant, which you can then modify for smaller or larger ones. If you are watering at the base of the plant, that is exactly the right way to do it, since that keeps moisture off the leaves, which can facilitate disease. Applying mulch can help keep moisture from evaporating, which means less watering; that and other tips are described in this article from Michigan State University.