I agree. I usually play with the geometry a little until it's as good as I can get it and then I go fly. These planes are not perfect, we are not perfect, so you are going to always get some degree of slack. the real thing to avoid is when it gets tighter as you deflect the rudder/surface.

But the general rules need to be followed as well as possible. For example if it's straght cables, no offset in the arm or control horn (clevis pin on hinge line). If it's a straight cable and there is offset in the control horn, there needs to be offset in the servo arm. If they are crossed cables there needs to be offset in the servo arm.

Take a look at SWB pull pull examples. It really summarizes it all.

http://www.swbmfg.com/rudex.html