Scaling streaming data

A development team's Kinesis Data Stream is throttling writes even though overall throughput is well below the stream's provisioned capacity. They suspect one shard is doing far more work than the others.

Use the Kinesis Partition Key Visualizer to explore how different partition key strategies affect record distribution across the 4 shards. Try each strategy in the dropdown, click "Generate 1000 events", and watch the bar chart and the max/min shard ratio.

Question: Which strategy creates the most lopsided shard load?