I have a few vegetables growing in containers. Let's say the soil is starting to dry out, but it's supposed to rain tomorrow. Would you fully water the plants now? Or just give them a bit of water to hold them over till the rain comes?
If the plants are in containers, you water as normal - unless rain is torrential and persistent, it doesn't make much impact on potted plants, especially as the season progresses and topgrowth/foliage increases in size, helping to keep even more rain off the soil in the pots. I'm assuming the containers have drainage holes...
I wouldn't recommend the habit of giving any plant "just a bit of water" if that means "less than it really needs". Over time it can lead to poor development of the plant, like a shallow root system to catch most of the "bits of water" in the short term at the expense of getting a proper supply of water and nutrients from deeper in the soil in the long term.
If you think the plant needs watering right now, then water it normally. If you are confident it will survive until it rains tomorrow, don't water it at all.
A complete answer would depend on the local climate, the type of plants you are growing, etc, etc - in gardening, "one size fits all" rarely applies.
It depends on what the aim is. If you want healthy looking plants, then sure, make sure that they have a regular supply of water. But over watering also results in (micro)nutrient loss from the soil as it gets washed into the lower layers beyond the reach of the roots. So, in this respect it might be better to retain the water in the soil (with mulching) rather then more frequent watering.
The other issues is the health benefits to you from eating the vegetables. If the plant is stressed and susceptible to more insect attack, it starts to activate greater defenses against insects etc, and this leads to higher concentrations of antioxidants and other plant chemical defenses. Often these chemicals are considered beneficial for human health, though the taste might then tend to being more bitter.