Backing up individual tables may be helpful for those experiencing issues with php limits corrupting the backup. You can back up the largest tables like the post and search tables individually. Select the rest of them as one backup. If you are having these issues you really need to look into using SSH instead as it takes php limitations out of the picture.
I do full backup every night, I have been meaning to include incremental backup. The backup itself is handled by automysqlbackup which I have been using very successfully for many years.
Not sure if it's possible to run that under shared hosting. It has multiple options including FTP to backup serveice like AWS, encryption of the backup or even emailing it. Of course emailing may not work with really large files because they may be rejected by incoming email server.
It's configurable but each day it creates a backup, the daily backups are rotated out so you have the last 7 days. Weekly backups are rotated out every 5 weeks and montly backups are rotated out every six months with default configuration. In my case they are saved to non public folder on the server, using Windows scheduler I schedule WinSCP to download the latest backup each night.
Any time I'm editing, updating or doing anything with phpBB files locally I always populate the local database with the latest backup to test it.
“Results! Why, man, I have gotten a lot of results! I have found several thousand things that won’t work.”
Attributed - Thomas Edison