Cucumbers only need around 2 inches of water per week to allow them to thrive and grow properly.
I would recommend watering the cucumber plants 2 to 3 times per week which is usually good enough although in drier weather you may need to water them more often if the soil becomes dry.
But as long as you're giving them at least 2 inches of water per week the cucumbers should thrive and grow.
If rainfall happens within that week then the cucumber plants usually don't require any watering until the next week of no rainfall.