What do you think is more critical? To allocate more resources or change architecture?

What about long term?

I'm planning to add a third node to the cluster. I believe this would reduce shards per index which I believe is very critical.
But will this be enough? Do I need to review the whole indexing strategy? I would be happy if I can avoid this because the code is a mess.

PS:
BTW, what do you mean by indexing strategy. Can you provide me a link or resource to study it?