The roofing looks very good! I'm not a professional :) but I do have one or two comments. The types of wood are divided into different durability classes and have different lifespans under the same conditions. Depending on the construction and weather conditions, it's hard to say whether a roofing will last long. If the structural wood protection is not observed, the hardest and most durable type of wood is useless. The construction will rot away faster than you can imagine. The most important thing about wooden constructions outdoors is that they are not exposed to constant moisture. Ideally, they should have no ground contact (which you don't have). The contact surfaces between the woods must be as small as possible to avoid stagnant moisture. You should observe if water accumulates anywhere and cannot dry quickly. Those will be the areas to start rotting first. Was end grain protection applied after cutting in the construction, for example? Otherwise, the wood can absorb moisture faster in these areas and cause cracking. I would say that coatings increase lifespan. However, it is unfortunately associated with effort. Whether the work is worth it is something everyone has to decide for themselves :). I tried to follow all these points as well as possible on my wooden terrace and will also regularly oil and maintain it. Let's see how long it lasts. But a wooden terrace is hard to compare with a wooden roofing. What I noticed positively after oiling is that water drains much better and does not partially penetrate the wood. (What a miracle :D)