A tip I picked up listening to gardeners' question time many seasons ago was to water in stages. I also always use a watering can - good exercise and you put in what the pot needs and no more.
- water early in the morning or late at night
- use half a can's worth per container and leave the plants to take in the water for 15 - 20 minutes
- then top up until you can see water coming through the bottom.
- Even in a dry spell the pots last a few days.