I dunno why you guys so obsessed on seat resevation. Most people here are not going to Japan during Golden Week. Even you going on Golden Week, due to JR dirty trick, you also won't get a seat.
I been To Japan so many times, entire Forumer here combine also can't more than me. I never ever once in my whole life sit on full passenger train (Limited Express
& Shinkansen) except Golden Week. Even Airport Express (NEX, Keisei Skyliner, Haruka , Nankai) more than 300 times, not even once full.
Even the most popular Kintetsu Shimakaze & Hinotori also never ever full.
You guys here really kanasai......