Why Japan needed the Katori training cruisers

Were the Katori-class training cruisers a waste of resources?

No; they were late and lightly armed, but Japan needed them to expand a training system that had fallen behind shipbuilding.

The lightly armed Katori class supplied training capacity for an expanding Japanese fleet. Ordering such ships around 1930, roughly a decade earlier, would have addressed that need sooner. They could also have been treated as auxiliaries. Japan's practice of building ships before training their personnel left the training system struggling to catch up, whereas other navies began recruiting before constructing the ships.