Using the yad installer.. (not sure if same is on the other installers)
I suggest a dialogue box be added saying that grub is installing while that happens
During the installation everything has a something visual (statusbar or dialogue box) while it is happening except for the grub install. Now there is a gap while grub installs that is noticeable and a novice may not be patient enough for it to end and exit
The new dialogue box could simply say ' Installing Grub ' and then on to the passwords
Thanks