Photoshop has Percentage as a unit for its ruler, and I find it very useful when one needs to center an element, or drag a guide in the middle or the third of the image, especially as one can stick to the ruler marks.
I always wondered why Illustrator did not have that functionality.
Why do we constantly have to adapt the way we interact with the software once we jump from one app to the other?
Consistency in the interface is a big plus to the customers that we are.
Indeed, it is difficult to have percentage guides when there are multiple artboards, but Photoshop dealt with that issue.
Percentage guides would be very useful for placing elements in the central location, or at the thirds, without habingto resolve to using a calculator.
Jack Harkin commented
2021 and this still hasn't come about
That would be an useful feature to add to Ai. Fingers crossed!
I've always wondered the same thing. In fact, I found this page while searching for how to do it.
This would be very helpful for translating web design mock ups. I'm more comfortable in Illustrator and usually start 'playing' around with designs in it before making changes to my website!
Vicki Loader commented
Would lovely useful. this feature to be included. In creating Surface Designs/Prints, Patterns, Repeats—or whatever you want to call them, being able to move/copy and item by percentage would be very useful. I do this in Photoshop, have created an action and it nearly automates my complex designs.