Lighter helicopters (e.g. 206, anything below B2) tend to be used for crew changes and spotting. No copilot required, but an extra pair of eyes is always useful! The picking up of water and dropping it can be developed into one complete smooth movement.
However, depending on the distance between the water and the fire, and whether you get proper airflow, you have to watch temperatures a lot more. If picking up from running water (e.g. a stream), take care not to get into a fast taxi.
cheers
Phil