[Taqwus]

It depends on the game setup, including your neighbors.

If you're on a crowded, tiny map and your Niefelheim neighbors are sending N9E4-blessed Niefel giants in your direction immediately, you need something to kill them -- fast.

If you're on a tiny map where other sides are sacrificing scales for a rampaging pretender that will rapidly out-expand you, he'll have many more resources to crush you before your scales are likely to matter much.

If you're on a massive map with relatively few nations, and very strong independents, and it's late era (so fewer easily accessible monster sacred units running around), scales will matter more than in the earlier case.