How to reduce the waiting time for choosing an operating system in the initial GRUB screen?

Question

GRUB

/etc/default/grub is set to GRUB_TIMEOUT=0, but it takes 30 seconds to wait.
How to reduce this time to a minimum?
I do sudo update-grub after the change.
OS: Linux Mint.
The LVM disk is (password-protected) completely.

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 5.4.0-70-generic"
#GRUB_TIMEOUT_STYLE="hidden"
GRUB_TIMEOUT=1
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
#GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash rootfstype=ext4 libahci.ignore_sss=1 raid=noautodetect selinux=0 plymouth.enable=0 lpj=11998664"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE="1280x1024"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
GRUB_DISABLE_LINUX_UUID="true"

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

export GRUB_MENU_PICTURE="/home/ez/Desktop/o7JRGzx-skyrim-wallpaper-1280x1024.jpg"
GRUB_SAVEDEFAULT="false"

sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/50_linuxmint.cfg'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
using custom appearance settings
Found linux image: /boot/vmlinuz-5.4.0-70-generic
Found initrd image: /boot/initrd.img-5.4.0-70-generic
Found linux image: /boot/vmlinuz-5.4.0-67-generic
Found initrd image: /boot/initrd.img-5.4.0-67-generic
Found linux image: /boot/vmlinuz-5.4.0-66-generic
Found initrd image: /boot/initrd.img-5.4.0-66-generic
Found linux image: /boot/vmlinuz-5.4.0-65-generic
Found initrd image: /boot/initrd.img-5.4.0-65-generic
Found linux image: /boot/vmlinuz-5.4.0-64-generic
Found initrd image: /boot/initrd.img-5.4.0-64-generic
Found linux image: /boot/vmlinuz-5.4.0-62-generic
Found initrd image: /boot/initrd.img-5.4.0-62-generic
Found linux image: /boot/vmlinuz-5.4.0-60-generic
Found initrd image: /boot/initrd.img-5.4.0-60-generic
Found linux image: /boot/vmlinuz-5.4.0-59-generic
Found initrd image: /boot/initrd.img-5.4.0-59-generic

Answer 1

Niva update the bootloader and it will hook the new values