On VH/VH, I found that for many years I was stuck defending Echigo against a steady stream of Takeda (once a year or 2), Jinbo (for 5 or so years until they got wiped out) and a few Hojo stacks. My troops and daimyo got heaps of experience, and sometimes didn't always have time to recover from the last siege (camps are good). I had hardly any income, and couldn't really afford anything, let alone take a province. Upgrading Echigo castle was critical, as the free defensive units, towers, taller walls and larger area were crucial. My monk was an expert demoraliser, and was crucial to keeping an eye on the all too numerous approaches, especially because he was the only agent I had for ages.
I only got a navy (apart from a few trade ships) after they started landing stacks on me, and they were there to stop that, and that's about it.
Eventually, after 10 years or so, I took Fukushima (they declared on me), and after that I headed NE and took over those nice provinces, which gave me a decent income for the first time. After that, it was steady progress against the Hojo and Takeda, and after an income hiccup at RD, on to Kyoto and the shogunate.
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