1
PROS VS CONS
Pros:

always syncs in real-time without using CPU, RAM, and storage speed

doesn't use any extra storage space
Cons:

may not support syncing individual files

doesn't work with Google Drive

always updates in real-time so the cloud software will constantly update (to avoid this,
run the cloud software at startup or a scheduled time only)

the cloud storage software interacts with the real files; this is mainly a problem with
OneDrive since it cannot sync while the file is open
2
FOLDER SYNC
Full documentation. Implementations:
AHK, e.g. "C:\OneDrive\Archived\SyncToYandex.ahk".
dedicated program, e.g mkLink. Then backup the program's settings/configurations to backup
all the mklinks configurations. This may be easier and more convenient to use.
3
INDIVIDUAL FILE SYNC
For individual files, omit the "/j" [1]. This only works for some file extensions. Check the
online website for the drive to see if the file syncs and the file size is the same. If not, it
doesn't work and you need to use a hard link (/h flag). A hard link moves the source file to
the destination and places the link at the original location instead. This allows you to reap the
benefits of this method but has the downside of moving the real files away from the original
location. The best method seems to be to use mklink for folders and use DSynchronize to
sync individual files to the sync folder (this will copy the files there). It's possible to not
waste extra storage space by using Yandex.Disk and enabling the online only option, which
will delete the files off your disk after uploading them.