How often should one water plants is often determined by rainfall.
Check your local forecast for the week ahead on one of the many Weather Forecast sites on the internet?
Generally all you have to do is pop your postcode in a designated spot to get your local weather forecast for the week ahead, this might eliminate the need to water at all.
If watering is required:
It is better to water well rather than often!
If too little water is applied, this will only moisten the upper layers of the soil and it will not get down to the root system where it is needed, necessitating further watering a short time after.
If in doubt, check the moisture levels by digging a hole adjacent to the plant/s with a trowel / spade to see how far the water has percolated down.
Watering in the evening allows the water to drain deep into the soil / compost over night, and early morning watering should be done before the heat of the sun builds up and causes evaporation.
If practical, move potted plants into the shade to protect from the sun until they recover.
Throw a sheet of fleece over those pots that can’t be moved.
Water only to an area consistent with the plants optimum spread.
Watering outwith this area will encourage weeds and create a moist surface that is suited to slugs and snails.