In this free tip, Pro Tools Expert team member Julian Rodgers demonstrates how to toggle the visibility of the grid lines in Pro Tools and how to change the grid value using a keyboard shortcut.
I still remember the day I first clicked on the Grid button to make the grid lines visible. It was a huge face-palm moment. I wished someone had told me sooner. There will be someone out there who is going to face-palm at this post just like I did. If it's you please share in the comments.
Try the shortcut for grid lines and see if you can track down the closely related shortcut for changing nudge values (clue - try different modifiers).