The Saturn V took longer than the N1. There were actually two versions of the Saturn V. The first one was build back in 0.18, and the second in 0.20 - that's about 6 months apart! I was figuring out the technique of making the tanks bigger in the first version and it wasn't that good. While building the second version, I realized that I can use cubic struts and solar panels to make mini fairings in which you can see between the stages of the rocket. I built and tested the N1 within an hour. If you turn off part clipping, you can tanks radially on a tank and rotate them into the center tank. On the N1, I simply made a core out of trusses, rotated the tanks 180 degrees, and put tanks around it.