Re-backing up a session as you edit a job

Stupid question time, but what's the best way to backup sessions as I work through edits? Here's what I'm doing.
Shoot, return to studio, download cards, immediately backup the shoot so I have 3 backups.
Edit shoot - rate files and share FPO's with client.
Backup.
Tone/grade/process files.
Backup.

As the RAW files are already on the backup drives, I don't need to back those up, but exactly what files do I need to backup and what's the best way to do that?

Thanks!