Each shard will only reside on a single node, so with one primary and one replica two nodes will be used for each index. Different indices will however be spread out across the available data nodes so all nodes will have data.
Whether to deviate from this sharding practice will depend on how much you index per day, now many indices you are indexing into and your query rate/patterns. Increasing the number of primary shards in order to spread out load may seem appealing, but can result in large number of very small shards which will be inefficient and cause a different set of problems.
If you tell us a bit more about your use case and expected data volumes and retention requirements we may be able to provide better giuidance.