People seem to be in a hurry to get the roof on. Is there a specific reason for this, like are the trusses particularly weather-sensitive? My trusses are 32 cm on the outside to accommodate insulation, so I would prefer to finish the exterior walls before attaching the roof to the trusses. I'm talking about wind protection boards and battens for the paneling, easier to reach and work when the roof isn't there. Does that seem reasonable?
The main reason you want to get the roof on as quickly as possible is reasonably that you want to make it wind and waterproof. It's never good if it rains into a construction, as it brings extra work, such as installing building description fans to dry out, and this in turn delays many other stages that cannot be carried out because of the moisture. Additionally, the risk also increases that mold could start forming, and you might trap moisture that got in because of the rain which has not dried out properly.