You should run it every time. For two reasons:
- You never know when backwards incompatible changes will be introduced
- If you don’t, you won’t be getting all of the updates including many of the security related updates.
Sure. As long as you understand the correct options to pass to grub-install
, you can make a hook for a given installation. In most(but not all) cases, it is sufficient to run grub-install --no-nvram
on UEFI installs.