Wondering how often to repaint weatherboards in Auckland is fair. The climate is mild, but it is also wet, and the sun on a west wall is not mild at all.
There is no honest single number. A sheltered Mount Eden villa on a decent system can go a long stretch between full repaints. A west-facing elevation in salt air, or a wall that never sees sun under trees, will not.
What actually decides it is the last job. If it was washed, scraped, primed on bare timber, and coated properly, you are inspecting rather than counting years. If it was a cheap coat over dirt and chalk, you might be looking at a much shorter cycle.
Washing once or twice a year does more for the film than adding a year to the diary. Mould, salt, and city grime hold moisture against the paint. A gentle wash is maintenance; a water blaster on tired weatherboard is how you find out the paint was already loose.
Look at south and west walls every year or two, even if the street front still looks fine. Do not wait until it is ugly. Once timber is wet behind the film, you are paying for repairs, not paint.
If you want a straight answer on your place, Bright Brush can look at it and tell you whether you are in maintenance-coat territory or a full repaint.