They will wilt and all the leaves will hang down, the amazing thing is when you water them they will go back to normal in less than 15 minutes. You can almost watch them grow.
Usually once a week aroks fro me but if they are growing good and the soil is drying out fast I'll go with twice a week.
It's easy to get ino the water onceor twice a day routine. I've had houseplants go a month without water and they grow just fine. Plants don't need as much water as you think.