As you have found out, your area requires frequent washing to control mold and algae. The schedule for washing you currently have should be sufficient. Repainting is a different story all together.
Washing with a chlorine solution will degrade the paint in time, so repainting will happen sooner. The best time to repaint your exteriors is when the paint has shown some fading and there is just a little peeling on the wood trim.
A good schedule is 5-7 years for repainting after the initial first paint job. The type of paint used will also affect this time frame. I recommend using an elastomeric paint instead is a standard 100% acrylic house paint. The elastomeric paint can take more repeated washings before fading and won't peel as easily.