I would like to be able to create a grid from the center of the canvas.
As it is, if I have a image (in this case a book template for printing) and the canvas is 2775w x 2175h (9.25"x7.25" at 300ppi) in order to create a GRID that fits (relates to) the canvas - so I can align objects to the "page" in my layout - I have to use a "Factor Calculator" (website) enter in fist value: 2775 generates to "factors" of that number (1,3,5,15,25,37,75,111,185,555,925,2775) enter in second value: 2175 generate factors (1,3,5,25,29,75,87,145,435,725,2175) Now in Photoshop Preferences >Guides, Grid & Slices > Gridline Every [choose a factor both values share: 1, 3, 5, 25, 75] this will create a grid that matches the canvas. In this example, 75 with two subdivisions worked well.
It would be nice if Photoshop could just do this calculation for us by checking a box "Create grid from center of canvas" and then use whatever divisions you want - just like normal (every px/inch/cm/% etc).
I learned this "trick" by following a youtube tutorial from 2014 🙂