The question is rather broad. There are many ways to repeat and arrange objects. Start with a specific example of something you want to do.
Say lets have a circle eg 200px in diameter then have 8 other circles perflectly fit around the outside egde of the circle in the middle.
Doing stuff like that, instead of manually positioning I hoped there might be a plug in that says, okay 1 center circle, how many objects around the outside? type in 8 then it automatically places them around and getting the correct size so that are perfeclty touching etc
Like this? You can probably make an action but it takes a few steps. You use the transform effect to configure the circles and then you scale one so they all touch then you draw the larger circle then you align the center with the center of the grouped circles then scale the circle to fit the outside dimension of the grouped circles.