Batching files together before uploading to Amazon S3 is a cost-effective strategy when dealing with a large number of small files. It reduces the number of PUT requests, which can lower costs, especially because S3 charges for each request. Uploading files individually would generate a significant number of requests, increasing the cost disproportionately in comparison to the actual storage used. Although using S3 Transfer Acceleration might speed up the transfer process and S3 Intelligent-Tiering could help with cost savings over time, they do not address the main cost issue related to the sheer number of PUT requests.