daily fresh water rinse
Lot's of good comments here. If you reference RR CSL 1235, the Note states that salt laden air may be encountered up to 75-150 miles inland. The operatior should use thier experience to determine the conditions they are operating in. Weather conditions including wind direction, temperature and humidity all have an effect on the amount of particulates in the air.
The fresh water rinses can also be good for the turbine as it rinses off salt particles, chemical an industrial stuff. However, if the bleed valve is not blocked shut like in a compressor/engine wash, it will take more time with the fresh water to get to the turbine.
The fresh water rinse is recommended at the end of the last flight of the day while the enigne is still warm is to rinse off particulates before the wheels are cooled. Once cooled, the fresh water is not as effective and once started again, the contamination can become baked onto the wheels.
Use your judgement and experience, every operational area can be differnt. The manufacture tries to provide the best information to maintain your enignes in all cirumstances.