This will depend on the sliding doors that you choose. The perfect overlap width is the width of the frame that vertically surrounds each door. This creates a seamless view when all of the doors are in the closed position.
When designing our wardrobes, we take great care to avoid any pull-out wardrobe interior components coinciding at any point where the doors overlap. Shelving and hanging space can usually be placed at these points without any impact on their functionality.
The overall width of the door opening is always less than the overall width of the doors to allow for the overlaps.