Comment 28 for bug 1273764

I'm dual-booting Windows 10 and Kubuntu 16.10 and I had the issue with the grub2 config file having a 10 second timeout then defaulting to 30 seconds upon boot.

I tried the workaround in post #8 which then caused my boot menu to be completely hidden. I then removed both files described in the workaround and removed the GRUB_HIDDEN_TIMEOUT value and ran sudo update-grub which seemed to have fixed my problem.
I have also had hibernation enabled for some time as noted in the GRUB_CMDLINE_LINUX_DEFAULT "resume=UUID=xxxxx" (swap partition) argument. I find hibernation extremely useful with laptops (I've removed the UUID for security reasons)

# 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=0
GRUB_HIDDEN_TIMEOUT=
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID=xxxxx"
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=640x480

# 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"