I posted about this before as regards to the magic sheet editor, but now I'm having the same problem with a live MS.
When I have overlapping objects, the selection of an object doesn't respect the border of the object so I keep selecting or deselecting the wrong object.
I have concentric circles of LED ribbon and to represent this on my MS, I made concentric circle objects with the smaller ones on top of the larger ones. Clicking on a circle often selects the circle next to and on top of it. This is slowing me way down.