The mistake is not the itinerary. It is the assumption that more places means more country.
Most first itineraries for Japan look identical. Tokyo, Kyoto, Osaka, a night in Hakone if someone has mentioned the mountain, and a bullet train ticket that gets used more than it should. The route is not wrong. It is simply the route everyone takes, which means it is optimized for coverage rather than for anything a traveler will actually remember.
The advisors who plan Japan well tend to make one structural decision early: they cut a city. Not because the cut city is unworthy, but because the time it releases is worth more than the place it removes. Three days in Kyoto is a checklist. Six days in Kyoto is a different country.
What fills that time is where firsthand knowledge stops being a nicety. A kaiseki reservation that requires a personal introduction. A temple that opens to guests an hour before the public. A guide in Kanazawa who worked as a lacquer apprentice for eleven years and will talk about it if asked correctly. None of this is bookable. All of it is arrangeable, by the right person.
The second structural decision is seasonal, and it is the one most travelers resist. Cherry blossom season is genuinely extraordinary and genuinely crowded, and the two facts do not cancel. An advisor who knows the country will sometimes argue for early November instead — the maples in Kyoto, the light, the absence of queues — and will lose that argument roughly half the time. The ones who win it tend to get a note afterward.
Japan rewards depth in a way that few countries do, partly because the surface is so well-designed that it is possible to have a completely pleasant trip and miss the place entirely. The difference between those two outcomes is rarely the hotel. It is almost always the decisions made three months earlier, by someone who had been.