I've just installed Debian Stretch 9.5. I've a dual boot (Debian + Windows) and the grub menu worked properly. Since I mainly use Debian I disabled grub menu in order to speed up the boot process (edit of the /etc/default/grub file) and it still works properly.
I wonder if there is a way to open the grub menu at boot time the few times I need to access Windows, having the grub menu disabled.
I found several posts where they suggested to press and hold Shift button during the boot, but it doesnt't work for me. Have you any suggestion? Thanks!