Comment 32 for bug 1814403

> If you still feel your system is showing the menu and timeout at every boot unnecessarily, or if you feel the default timeout is too long, please file a separate bug with the information specific to your system and particular case so we can look into it

In this case please look into https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1815002 for efi+btrfs combination.