The case for leaving later
Why the best window is usually two weeks after everyone else has gone home.
Peak season is a scheduling artefact. It exists because school holidays and statutory long weekends land where they land, not because the country is at its best in the second week of July.
What changes
Campgrounds empty out. Light gets longer and lower. Bugs thin, then stop. Water levels drop, which turns some crossings from a judgement call into a non-event. The trade is that services close, and closing dates are the thing to actually check — not the weather.
Peak season is a scheduling artefact, not a verdict on when the country is at its best.
The risk shifts rather than disappearing. Fewer people on the road means fewer people to help, and a recovery that would have been an inconvenience in August becomes a long wait in October. Go later, but go better equipped, and tell someone your route.