In one of my programs I can select a square (any subject) and enter 30 horizontal copies and 20 vertical copies, and I can enter a specific amount of spacing between each shape, or I can enter a specific distance between the center points. Easy and intuitive.
I am looking for the same feature in Illustrator. The closest I am seeing is Effects>Transform and Distort.
There are a couple of quick ways to do that in Illustrator (including actions, graphic styles etc.).
There are also scripts that can do it. One of them that I'd recommend is called Gridder, provided by Alexander Ladygin. Among other things it has a useful option to use (or not use) Illustrator's Transform effect to make the grids.