When you are working in an assembly it's not unusual to copy-and-paste a part or sub-assembly in the assembly or from one assembly to another. The problem with doing this with the marking menu or the classic menu is when you RMB click somewhere on the screen you get the popup menu open and where you clicked is either the lower left corner of the classic menu or the middle of the selection buttons at the bottom of the marking menu. Once you do that you have to move to the top of the menu to select PASTE. Problem is the item you're pasting in gets pasted at the location of PASTE on the menu, *NOT* where you first clicked. So there is basically no way to even roughly place the part where you want as it's dependent upon where the PASTE selection ends up in the popup menu.
Would be a LOT BETTER if it pasted where you RMB clicked rather than where the PASTE command is in the menu. And yes, I know you can do CTRL+V but doesn't mean this should work like this.