You don't have to water all of your vegetables all of the time. The first important time is during plant establishment. Direct sown seed will seek out water relatively efficiently, but plants planted out from modules or pots have tiny self-contained root balls and are unused to fending for themselves, so these will need plenty of cosseting as the roots stretch out. The second priority is when fruits or tubers or pods are swelling. It is always best to try and water at the end of the day. There is however an exception when it comes to courgettes, pumpkins and their like, which are prey to grey mould if the leaves are left damp over night. Except when watering delicate seedlings.
You should also remove the rose attachment from your watering can and water direct to the base of the plant, this to give a good slug of water into the soil and also avoids splashing the leaves which if the water has not run off of the leaves before sun rises could cause burning of the leaves.