What is the correct way to use Dutch banks? I feel like I have been relying on them too much.

Since you only get 50 villagers, can the Dutch economy function on banks alone? Currently, I stop mining coin once I have 4 banks and then use cards to build more. I usually play with 25 villagers on food and 25 villagers on wood. I also build fishing boats whenever I can for whales.

Is this wrong? You can have up to 10 banks by the imperial age, so I thought that was enough but I wanted to hear your thoughts.