Curious to know how rclone decides the order in which to process files, whether its for uploading, size checking, downloading, or everything else. From observation, it doesn’t seem to be alphabetical, nor is it by size.
The order rclone does things, eg upload, size, download, etc is the order that rclone ls lists things.
If you set --checkers 1 and --transfers 1 rclone will do everything in the order your cloud provider (or local disk) returns it in a directory listing, which might even be alphabetical.
However for checkers & transfers > 0 then rclone processes all the directories in independent threads and combines the output, so the order is heading towards random.