The latency for small files and ranges of large files is pretty similar on most storage platforms, but there are some exceptions like Cloudflare R2.
The main reason PMTiles is one file and not two or more files is that it enables atomic updates in-place (which every mature storage platform supports) as well as ETag content change detection in downstream caches. All of the server and serverless implementations at http://github.com/protomaps support this now for AWS, S3-compatible storage, Google Cloud, and Azure.
The main reason PMTiles is one file and not two or more files is that it enables atomic updates in-place (which every mature storage platform supports) as well as ETag content change detection in downstream caches. All of the server and serverless implementations at http://github.com/protomaps support this now for AWS, S3-compatible storage, Google Cloud, and Azure.