"Delete old backups" - Ability to specify a decimal number of days

I would like to request the ability to specify a fractional number of days in the "Delete old backups" field when setting up (and editing) a scheduled backup.

I currently have a backup script that runs hourly, but I don't really need more than a few hours history to be saved (as I also have a backup which runs daily)

Therefore, I would like to be able to specify a number of days such as '0.25' (6 hours).

Would this be possible?

Thanks!

Adam