So I have a question about leveling buildings.

My base right now is around 52-53 lv, and leveling up barracks, dojo or residence is no-brainer because obvious bonuses.
However is there any point in leveling port, forge or lab? Yes, you get 100 koban every 5 levels, but that's rather bonus than target itself.

My research level are way behind my lab level, so no rush here, I haven't seen any rise of forging success % with blacksmith gaining levels and I see no bonus in leveling port.

Is it not worth it and I should just keep leveling castle and keep dojo, barracks and residence as close as possible or am I missing something?