I'd come straight back for the 3, but you can't go wrong w 2 rails either bcuz if you're short or wide on the 3 , the 4 always goes in the corner by the 9 holding center table for ya. The out shot is getting good shape on the 4.I'd go the 2 rails backwards but the main reason the pros will likely get out is they'll take the rest of the out as it comes. For instance, there are 5 open pockets for the four. TRY and get outta line on the 3.
You can also go forward and you have the 3 up table or even in the side if you know the angle. You don't approximate or try angles. You shoot them as you know they'll play out.