I definately was when I forgot to fit the pressure regulator. Normally though only a small amount is wasted but with the local soil being heavy clay and with my house being on a hill any excess was travelling down to the next house down.

The thing with normal drip irrigation is that it doesn't know when the soil is saturated or dry so you have to adjust the system to tilt the flow rate towards the drying out side. Consequently when the soil is wet the excess is channeled away to stop the roots rotting in the pots.