The efibootmgr help output states:
-t | --timeout seconds set boot manager timeout waiting for user input.
But where does this timeout and user input occur?
It doesn't appear to affect boot managers like GRUB or rEFInd, which have input and timeout parameters in their own configuration files. It also doesn't seem common for a motherboard BIOS to show a boot selection options with a timeout (they typically either boot automatically to the first available option, or allow selection without a timeout if the setup utility is manually invoked).
Is this an outdated option or is there some firmware or software whose behaviour is controlled by this parameter?