This is a good point. It can get confusing
we make a triple bypass 3.0 for the Ford Raptor and most people have a hard time even relaying what it feels like or distinguishing compression problems from rebound problems let alone dialing it in. So we have a recommended settings chart for a couple different scenarios so you can always get back to a back a base line
see page 3 below
http://www.iconvehicledynamics.com/wp-content/uploads/2015/03/I95201_REVB.pdf
the CDC shocks have 1 knob with 10 settings that controls compression only. Rebound is set internally and once we have tuned it for the vehicle is less of a "personal preference" then compression (although if you wish you can revalve this internally)
the adjuster internals have a high speed blow off valve so you cant over do it on high speed valving and the knob mostly effects low and mid speed. you cant really screw it up, if you want it smother put it on S, if you want to drive hard or are loaded put it on H. 4 is calibrated to be the same as the non adjustable version so you can go both harder and softer.